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Guide

SPSS: From data preparation to reporting

Start with your research question and data structure, not a familiar SPSS button. Use ResearchKit's existing test reasoning, follow the matching IBM SPSS procedure, then check assumptions, effect size, output and reporting in context.

Updated Research stage: Collect and analyseNot yet checked by a named reviewer

What SPSS is and what this guide is

IBM SPSS Statistics is statistical software for managing data, running analyses and producing tables and charts. It is not a research design and it does not choose a defensible analysis on your behalf. ResearchKit is independent of IBM: this guide explains an educational workflow and links to IBM's own documentation; ResearchKit does not provide an installer, license or technical support for SPSS.

The Lab reads shared ResearchProjectDraft context when a workspace is open. It does not import an SPSS file, upload data, edit the project or save new SPSS state. Menu instructions and feature availability below are checked against IBM SPSS Statistics 32 documentation; dialog labels and licensing may vary by release, operating system and edition. Confirm a path in the documentation for the version you use.

  1. Research question and design
  2. Variables and data preparation
  3. Descriptive checks
  4. Select a test with the Statistical Test Finder
  5. Run the mapped procedure in SPSS
  6. Review assumptions with the Assumption Checker
  7. Calculate a suitable effect size
  8. Read output and interpret the reported values
  9. Write and preserve the analysis report

Recognize the editor, output and syntax

The Data Editor has two complementary views: Data View contains case values; Variable View contains the variable definitions and labels applied to those values. The Output Viewer collects procedure tables, notes and charts. The Syntax Editor holds commands that can be inspected, saved and rerun. Menu dialogs can paste their corresponding syntax, giving you a record of how an analysis was specified.

SPSS windows and common file types Scroll sideways to see every column.
Window or filePurpose
Data Editor: Data ViewRows are cases; columns are variables and their recorded values.
Data Editor: Variable ViewDefine names, labels, value labels, missing values, storage formats and measurement level.
Output Viewer (.spv)Review and save the tables, warnings and charts produced by procedures.
Data file (.sav)Save an SPSS Statistics dataset and its variable metadata.
Syntax file (.sps)Preserve executable commands and analysis decisions separately from the data and output.

Save the data, syntax and output as distinct project artifacts. Exporting output for a report is separate from keeping the editable SPSS output file; use the export options present in your installed version and verify the exported tables after conversion. IBM menu labels and available file formats can change between releases.

Start with the research question and variables

Write down the question, target population, design and unit of analysis first. Mark the outcome, predictor or grouping factor, any covariate, and whether the question compares groups, examines association, predicts an outcome, or compares a single sample with a value. This question-first sequence follows established research-methods teaching (Field, 2018; Howell, 2013). The Statistical Test Finder owns the deterministic test-selection reasoning; the SPSS Lab only maps an already selected method to a procedure.

Keep question, variable roles and study structure distinct Scroll sideways to see every column.
QuestionVariable rolesStructure to record
Do two groups differ in a score?Quantitative outcome; categorical grouping variableSeparate participants or the same/matched participants?
Are two measurements associated?Two variables; neither is inherently the outcome for correlationOne pair of values per case; inspect the form of association
Can predictors estimate an outcome?Outcome plus one or more predictorsPredictor coding, model specification and residual diagnostics
Do category counts match stated proportions?One categorical variable and expected proportionsObserved independent counts; expected proportions justified in advance
Are two categories associated?Two categorical variablesOne observation per case in a cross-tabulation cell
Outcome (quantitative)Weekly working hours
Comparison value (stated in advance)40 hours
One sample compared with a stated valueThe mean of one quantitative variable, weekly working hours, is compared with a value stated in advance: the 40 hours in the contract.
Grouping variable (independent variable)Bank type
  • Public banks
  • Private banks
Outcome (dependent variable)Job satisfaction
Two independent groups compared on one outcomeA grouping variable, bank type, splits participants into two separate groups, public and private; their mean job satisfaction is compared.
First measurementScore before training
Second measurement, same participantsScore after training
The same participants measured twiceEach participant's score before training is compared with their own score after training.
First variable (quantitative)Study time
Second variable (quantitative)Exam score
Two quantitative variables examined togetherStudy time and exam score are examined together, with no variable treated as the outcome.
Predictor (independent variable)Study hours
Outcome (dependent variable)Exam score
One predictor used to estimate an outcomeStudy hours, the predictor, points to exam score, the outcome being predicted.
Predictor 1Study hours
Predictor 2Attendance
Outcome (dependent variable)Exam score
Several predictors used together to estimate an outcomeTwo predictors, study hours and attendance, both point to exam score. Each one's contribution is estimated while holding the other constant.
First variable (categorical)Gender
Second variable (categorical)Employment status
Two categorical variables examined togetherGender and employment status, both categorical, are cross-tabulated to see whether they are associated.
Categorical variable (observed counts)Service channel chosen
Expected counts (stated in advance)Equal shares for every channel
One categorical variable compared with expected sharesThe counts of customers choosing each service channel are compared with the counts expected if every channel were chosen equally often.

Create, code and check the data file

In the Data Editor, Data View organizes cases as rows and variables as columns. Variable View records metadata for each column: a concise unique variable name, a human-readable label, value labels for category codes, missing-value definitions, and a measurement level. SPSS uses nominal, ordinal and scale as its measurement labels; scale combines interval and ratio for many procedures. A software label never repairs an invalid measurement or study design.

Coding is defined by the researcher and documented in the codebook; no code is universal. For one questionnaire, gender might use 1, 2 and 3 for locally defined responses; education might use ordered codes from secondary study to doctoral study; a Likert item might use 1 to 5 from strongly disagree to strongly agree. State every label, preserve meaningful missing categories, and do not treat arbitrary category numbers as measurements with equal intervals.

  • Keep an untouched source copy; record the imported file, date and any transformations.
  • Check IDs and duplicate cases, valid ranges, category labels, impossible combinations, missing-value codes and each analysis's eligible N.
  • Inspect frequency tables for categorical variables and distributions/plots for quantitative variables before choosing summaries or inferential methods.
  • Reverse-code only the specified items using the documented scale endpoints; verify the resulting minimum and maximum.
  • Compute a total or mean scale score only when the item definitions and missing-item rule justify it; keep the source items and record the scoring rule.
  • For regression, encode categorical predictors with explicit contrasts/dummy variables; the numeric codes alone do not model categories correctly.
  • Record exclusions, recodes, computed variables and outlier decisions before interpreting outcomes.
Example codebook entries (codes are study-defined, not standards) Scroll sideways to see every column.
VariableType / levelExample documentation
departmentCategorical / nominal1 = Operations; 2 = Finance; 3 = Marketing. Codes are local to this example.
educationCategorical / ordinal1 = Secondary; 2 = Bachelor's; 3 = Master's; 4 = MPhil; 5 = PhD. Verify order and labels for the study.
agreement_itemOrdered response / ordinal1 = Strongly disagree through 5 = Strongly agree; document any reverse scoring and its formula.

Describe before testing

Frequencies can show counts, percentages and, when requested, descriptive statistics and charts. Descriptives summarizes numeric variables with N, mean, minimum, maximum, standard deviation and variance. Explore supports distributions, percentiles and graphical checks. Match the statistic to the measurement: mode/frequencies for categories, median and quartiles for ordered or skewed values, and mean/SD for quantitative values where those summaries are informative.

  • Analyze → Descriptive Statistics → Frequencies: use for category counts/percentages and optionally mode, median, quartiles, charts or other statistics.
  • Analyze → Descriptive Statistics → Descriptives: use for numeric summaries such as mean, SD, variance, range, minimum and maximum.
  • Analyze → Descriptive Statistics → Explore: use to inspect distributions, percentiles and potential outliers alongside plots.
  • An outlier or non-normality flag prompts inspection and methodological reasoning; it does not automatically invalidate a method or require a nonparametric replacement.
Days of training attended by nine employees (invented for illustration) Scroll sideways to see every column.
EmployeeDays
12
23
33
43
54
65
75
86
914
Summaries of the training days Scroll sideways to see every column.
StatisticValueWorkingWhat it tells you
Mean5.0(2 + 3 + 3 + 3 + 4 + 5 + 5 + 6 + 14) ÷ 9 = 45 ÷ 9The average, pulled upwards by the one employee with 14 days.
Median4.0The 5th of the 9 values in orderThe middle employee attended 4 days: half attended fewer or the same, half the same or more.
Mode33 appears three times, more than any other valueThe most common number of days.
Standard deviation3.61√[ Σ(x − x̄)² ÷ (n − 1) ]Values typically lie a few days from the mean; the one large value inflates it.

Choose the analysis before opening its dialog

The Statistical Test Finder asks only for information relevant to the question and shows candidate methods, uncertainty, reasons and assumptions. After deciding with that tool and your research context, use the SPSS Lab to locate the corresponding procedure. The one-variable goodness-of-fit chi-square and two-variable chi-square test of independence have different inputs and answer different questions.

Choosing a statistical test: a decision treeFollow the questions from the top. Each path ends in the tests commonly used for that situation. It shows common practice, not the only valid choice.

What are you trying to find out?

  • Describe a variable

    How is the variable measured?

    • Nominal (categories)

      Commonly used: Mode, Frequency

      May also fit: Percentage

    • Ordinal (ordered categories)

      Commonly used: Median

      May also fit: Frequency, Mode

    • Interval or ratio, roughly symmetric

      Commonly used: Mean, Standard deviation

      May also fit: Median

    • Interval or ratio, skewed

      Commonly used: Median

      May also fit: Mean, Standard deviation

  • Compare groups, times or a target value

    What are you comparing?

    • One group with a stated value

      How is the outcome measured?

      • Interval or ratio

        Commonly used: One-sample t-test

      • Nominal (categories)

        Commonly used: Chi-square goodness-of-fit test

    • Separate groups of different people (independent)

      How is the outcome measured?

      • Interval or ratio

        How are the groups arranged?

        • Two groups, one grouping variable

          Commonly used: Independent-samples t-test

        • Three or more groups, one grouping variable

          Commonly used: One-way ANOVA

        • Two grouping variables together

          Commonly used: Two-way ANOVA

          May also fit: Independent-samples t-test, Multiple regression

          Each grouping variable can have two or more categories.

        • Groups compared while controlling for a numeric covariate

          Commonly used: ANCOVA

          May also fit: Independent-samples t-test

      • Ordinal

        How many groups?

        • Two

          Commonly used: Mann–Whitney U test

        • Three or more

          Commonly used: Kruskal–Wallis test

      • Nominal (categories)

        Commonly used: Chi-square test of independence

        May also fit: Fisher's exact test

        The same test applies with more groups or categories.

    • The same people measured more than once (paired)

      How is the outcome measured, and how many times?

      • Interval or ratio, twice

        Commonly used: Paired-samples t-test

      • Interval or ratio, three or more times

        Commonly used: Repeated measures ANOVA

      • Ordinal, twice

        Commonly used: Wilcoxon signed-rank test

  • Examine a relationship between two variables

    How are the two variables measured?

    • Both interval or ratio, roughly normal

      Commonly used: Pearson correlation

      May also fit: Simple linear regression

    • At least one ordinal

      Commonly used: Spearman's rank correlation

  • Predict or explain an outcome

    How is the outcome measured, and how many predictors?

    • Interval or ratio, one quantitative predictor

      Commonly used: Simple linear regression

      May also fit: Pearson correlation

    • Interval or ratio, two or more predictors

      Commonly used: Multiple regression

    • Two categories, such as yes or no

      Commonly used: Logistic regression

  • Examine categories

    How many categorical variables?

    • One, compared with expected shares

      Commonly used: Chi-square goodness-of-fit test

    • Two, examined together

      Commonly used: Chi-square test of independence

      May also fit: Fisher's exact test

Common statistical tests compared Scroll sideways to see every column.
Common candidate testResearch purposeOutcomeGroups or variablesStructureKey assumptionsAlternative or related method
One-sample t-testDoes the mean of a quantitative outcome differ from a known or hypothesised value?One quantitative variable (interval or ratio).None: a comparison value stated in advance. Groups: One.Not applicable: one measurement per participant.
  • Interval or ratio measurement
  • Independence of observations
  • Normality
  • No influential outliers
One-sample Wilcoxon signed-rank test
Independent-samples t-testDo two separate groups differ in the mean of a quantitative outcome?One quantitative variable (interval or ratio).One grouping variable with two categories. Groups: Two.Independent: each participant is in one group only.
  • Interval or ratio measurement
  • Independence of observations
  • Normality
  • Homogeneity of variance
  • No influential outliers
Mann–Whitney U test
Paired-samples t-testDoes the mean of a quantitative outcome change between two measurements of the same people?One quantitative variable, measured twice.Time or condition: two measurements. Groups: One group, two measurements.Paired: each participant contributes both measurements, or participants are matched in pairs.
  • Interval or ratio measurement
  • Paired observations
  • Normally distributed differences
  • No influential outliers
Wilcoxon signed-rank test
One-way ANOVADo three or more independent groups differ in the mean of a quantitative outcome?One quantitative variable (interval or ratio).One grouping variable (factor) with three or more categories. Groups: Three or more.Independent: each participant is in one group only.
  • Interval or ratio measurement
  • Independence of observations
  • Normality
  • Homogeneity of variance
  • No influential outliers
  • Adequate group sizes
Kruskal–Wallis test
Two-way ANOVADo two grouping variables, separately and together, relate to differences in a quantitative outcome?One quantitative variable (interval or ratio).Two grouping variables (factors), each with two or more categories. Groups: Every combination of the two factors' categories.Independent: each participant is in one combination only.
  • Interval or ratio measurement
  • Independence of observations
  • Normality
  • Homogeneity of variance
  • No influential outliers
  • Adequate group sizes
Aligned rank transform ANOVA
ANCOVADo groups differ in the mean of a quantitative outcome once a quantitative covariate is allowed for?One quantitative variable (interval or ratio).One or more grouping variables, plus one or more quantitative covariates. Groups: Two or more.Independent: each participant is in one group only.
  • Interval or ratio measurement
  • Independence of observations
  • Normally distributed residuals
  • Homogeneity of variance
  • Linearity
  • Homogeneity of regression slopes
  • Covariate independent of the grouping
  • No influential outliers
Quade's rank analysis of covariance
Chi-square test of independenceAre two categorical variables associated?One categorical variable.A second categorical variable. Groups: Two or more categories of each.Independent: each participant is counted once, in one cell.
  • Categorical variables
  • Independence of observations
  • Adequate expected counts
Fisher's exact test
Chi-square goodness-of-fit testDo the counts in one categorical variable's categories match shares stated in advance?One categorical variable.None: expected proportions stated in advance. Groups: Two or more categories.Independent: each participant falls in one category.
  • Independent observations.
  • Each participant falls in exactly one category.
  • Expected counts of at least 5 in most categories.
Chi-square test of independence
Pearson correlationDo two quantitative variables go together in a straight line, and how strongly?First variable: quantitative.Second variable: quantitative. Neither needs to be the outcome. Groups: Not applicable: one group, a pair of values per participant.Each participant contributes one value of each variable.
  • Interval or ratio measurement
  • Independence of observations
  • Linearity
  • Normality
  • No influential outliers
Spearman's rank correlation
Simple linear regressionHow well can a quantitative outcome be predicted from one predictor, and how much does it change per unit of the predictor?One quantitative variable.One predictor, usually quantitative. Groups: Not applicable.Each participant contributes one value of each variable.
  • Interval or ratio measurement
  • Independence of observations
  • Linearity
  • Normally distributed residuals
  • Homoscedasticity
  • Independent errors
  • No influential outliers
Spearman's rank correlation
Multiple regressionHow well do several predictors together predict a quantitative outcome, and what does each add while the others are held constant?One quantitative variable.Two or more predictors, quantitative or categorical (entered as dummy variables). Groups: Not applicable.Each participant contributes one value of each variable.
  • Interval or ratio measurement
  • Independence of observations
  • Linearity
  • Normally distributed residuals
  • Homoscedasticity
  • Independent errors
  • No influential outliers
  • No multicollinearity
Robust (heteroscedasticity-consistent) standard errors

The table scrolls sideways on narrow screens.

Parametric and rank-based methods answer different versions of a question Scroll sideways to see every column.
SituationCommon parametric methodPossible rank/count methodDecision point
Two independent groups, ordered or quantitative outcomeIndependent-samples t-testMann–Whitney UEstimand, measurement, distribution, design and robustness
Two paired measurementsPaired-samples t-testWilcoxon signed-rankAnalyze pairing; for t, consider the distribution of differences
Three or more independent groupsOne-way ANOVAKruskal–WallisA global test does not identify which groups differ
Two quantitative measurementsPearson correlationSpearman rank correlationLinear versus consistently monotonic association and influential outliers

Do not switch methods solely because a preliminary normality test crosses a threshold. Consider what parameter the research question concerns, the actual distribution and outliers, sample size, independence, robustness, and whether the alternative answers the same question. The Assumption Checker describes checks and alternatives; the researcher remains responsible for the decision.

Follow the SPSS procedure for the selected method

These procedure cards reuse ResearchKit's analysis-method IDs, test profiles and assumption knowledge. Menu labels and selected options below were checked against IBM SPSS Statistics 32 documentation. Most referenced procedures require Statistics Base; verify your licensed edition. A single menu path does not establish that the method suits the design.

One-sample t-test

Compares the mean of a numeric outcome in one sample with a known or hypothesised value, such as a target or a published average.

It compares one sample's mean with a value set before the data were collected.

Why not another test?

  • Independent-samples t-test: The independent-samples t-test needs a second group of participants; here the comparison is with a fixed value.

SPSS procedure

One-Sample T Test

  1. Analyze
  2. Compare Means
  3. One-Sample T Test

IBM documents this path for SPSS Statistics 32. Menu wording, dialog layouts and available options may differ by version, operating system and licensed edition; consult the IBM documentation for the installed version.

Verify this procedure in IBM SPSS Statistics 32 documentation

Variable placement

  • Test Variable(s): One or more quantitative outcome variables.
  • Test Value: The comparison constant specified before inspecting the results.

Options and output

  • Request the confidence interval and effect-size estimate where available.
One-sample t-test: output to inspect Scroll sideways to see every column.
SPSS outputWhat to inspect
One-Sample StatisticsN, mean and standard deviation.
One-Sample TestTest value, mean difference, t, df, two-sided p and confidence interval.

Assumptions

  • Interval or ratio measurement: The outcome is measured on a numeric scale with equal intervals between values.
  • Independence of observations: Each participant's data are unrelated to every other participant's, and each participant contributes once.
  • Normality: The outcome is approximately normally distributed within each group.
  • No influential outliers: No single case distorts the result.

Effect size

Cohen's d for a one-sample comparison; state the standardizer and use the calculator for an independently documented calculation.

Reporting

Report M, SD, the comparison value, t(df), p, effect size and a confidence interval where available.

Use the Results Interpretation Assistant to interpret the values you enter in the context of your research question and project. SPSS output alone does not establish a causal or practically important result.

Independent-samples t-test

Compares the means of a numeric outcome between two separate groups.

It compares the means of two independent groups on a quantitative outcome.

Why not another test?

  • Paired-samples t-test: The paired-samples t-test is for the same participants measured twice, or matched pairs; here each participant is in one group only.
  • One-way ANOVA: One-way ANOVA is usually used for three or more groups. With two groups it gives the same answer as the equal-variances t-test (F = t²).

SPSS procedure

Independent-Samples T Test

  1. Analyze
  2. Compare Means
  3. Independent-Samples T Test

IBM documents this path for SPSS Statistics 32. Menu wording, dialog layouts and available options may differ by version, operating system and licensed edition; consult the IBM documentation for the installed version.

Verify this procedure in IBM SPSS Statistics 32 documentation

Variable placement

  • Test Variable(s): One or more quantitative outcomes.
  • Grouping Variable: One variable identifying two independent groups; define the two group codes.

Options and output

  • Review Levene's homogeneity-of-variance test and use the corresponding equal-variance or unequal-variance row.
  • Request the confidence interval and effect-size estimate where available.
Independent-samples t-test: output to inspect Scroll sideways to see every column.
SPSS outputWhat to inspect
Group StatisticsGroup N, mean and standard deviation.
Independent Samples TestLevene result, the appropriate t-test row, t, df, two-sided p, mean difference and confidence interval.

Assumptions

  • Interval or ratio measurement: The outcome is measured on a numeric scale with equal intervals between values.
  • Independence of observations: Each participant's data are unrelated to every other participant's, and each participant contributes once.
  • Normality: The outcome is approximately normally distributed within each group.
  • Homogeneity of variance: The groups being compared have similar variances.
  • No influential outliers: No single case distorts the result.

Effect size

Cohen's d or Hedges' g for independent groups; identify the pooled-SD convention and use the calculator's matching mode.

Reporting

Report each group's M and SD, then t(df), p, mean difference, effect size and confidence interval where available.

Use the Results Interpretation Assistant to interpret the values you enter in the context of your research question and project. SPSS output alone does not establish a causal or practically important result.

Paired-samples t-test

Compares the means of a numeric outcome measured twice on the same participants, such as before and after.

It analyses each participant's change, comparing the mean of the differences with zero.

Why not another test?

  • Independent-samples t-test: The independent-samples t-test treats the two sets of scores as coming from different people, ignoring that each participant is compared with themselves.

SPSS procedure

Paired-Samples T Test

  1. Analyze
  2. Compare Means
  3. Paired-Samples T Test

IBM documents this path for SPSS Statistics 32. Menu wording, dialog layouts and available options may differ by version, operating system and licensed edition; consult the IBM documentation for the installed version.

Verify this procedure in IBM SPSS Statistics 32 documentation

Variable placement

  • Paired Variables: Two quantitative measurements for the same cases, entered as a pair.

Options and output

  • Check the direction of the pair order before interpreting the mean difference.
  • SPSS 32 offers several standardizers for its optional Cohen's d and Hedges correction; choose and report the intended convention.
Paired-samples t-test: output to inspect Scroll sideways to see every column.
SPSS outputWhat to inspect
Paired Samples StatisticsN, mean and standard deviation for each measurement.
Paired Samples CorrelationsThe correlation between the paired measurements; it is not the change test.
Paired Samples TestMean difference, t, df, two-sided p and confidence interval.

Assumptions

  • Interval or ratio measurement: The outcome is measured on a numeric scale with equal intervals between values.
  • Paired observations: Each measurement in one condition is matched to one in the other, usually the same participant measured twice.
  • Normally distributed differences: The differences between each pair of measurements are approximately normal.
  • No influential outliers: No single case distorts the result.

Effect size

Paired standardized mean difference. Specify whether the denominator is the SD of differences (d_z) or an average marginal SD (d_av); these are not interchangeable.

Reporting

Report each time/condition's M and SD, mean change, t(df), p, the specified paired effect-size convention and confidence interval where available.

Use the Results Interpretation Assistant to interpret the values you enter in the context of your research question and project. SPSS output alone does not establish a causal or practically important result.

Chi-square test of independence

Tests whether two categorical variables are associated.

It compares the counts in a cross-tabulation with the counts expected if the two variables were unrelated.

Why not another test?

  • Independent-samples t-test: A t-test compares means, which need a quantitative outcome; here both variables are categories.

SPSS procedure

Crosstabs: Chi-Square Test of Independence

  1. Analyze
  2. Descriptive Statistics
  3. Crosstabs
  4. Statistics
  5. Chi-square

IBM documents this path for SPSS Statistics 32. Menu wording, dialog layouts and available options may differ by version, operating system and licensed edition; consult the IBM documentation for the installed version.

Verify this procedure in IBM SPSS Statistics 32 documentation

Variable placement

  • Row(s): One categorical variable.
  • Column(s): A second categorical variable; each case contributes to one cell.

Options and output

  • Select Chi-square in Statistics.
  • Select observed and expected counts and suitable percentages in Cells.
Chi-square test of independence: output to inspect Scroll sideways to see every column.
SPSS outputWhat to inspect
CrosstabulationObserved counts, expected counts and the percentages appropriate to the question.
Chi-Square TestsPearson chi-square, df, asymptotic significance and footnotes about expected counts.

Assumptions

  • Categorical variables: Both variables are measured in categories.
  • Independence of observations: Each participant's data are unrelated to every other participant's, and each participant contributes once.
  • Adequate expected counts: The counts expected in each cell, if the variables were unrelated, are large enough.

Effect size

Cramér's V for general tables; phi is appropriate for a 2 × 2 table. IBM documents both in Crosstabs statistics.

Reporting

Report χ²(df, N), p, the relevant crosstab percentages and phi or Cramér's V; do not infer causation.

Use the Results Interpretation Assistant to interpret the values you enter in the context of your research question and project. SPSS output alone does not establish a causal or practically important result.

Chi-square goodness-of-fit test

Tests whether the counts in one categorical variable's categories match expected proportions, such as equal shares or known population shares.

It compares the observed count in each category with the count expected from shares stated in advance.

Why not another test?

  • Chi-square test of independence: The chi-square test of independence needs two categorical variables; here there is one, compared with expected shares.

SPSS procedure

Legacy Dialogs: Chi-Square Test (Goodness of Fit)

  1. Analyze
  2. Nonparametric Tests
  3. Legacy Dialogs
  4. Chi-Square

IBM documents this path for SPSS Statistics 32. Menu wording, dialog layouts and available options may differ by version, operating system and licensed edition; consult the IBM documentation for the installed version.

Verify this procedure in IBM SPSS Statistics 32 documentation

Variable placement

  • Test Variable List: A categorical variable whose observed category counts are compared with equal or specified expected proportions.

Options and output

  • Set expected values to the proportions justified before examining the observed counts.
  • Inspect the expected frequencies; IBM notes expected frequencies should be at least 1 and no more than 20% below 5.
Chi-square goodness-of-fit test: output to inspect Scroll sideways to see every column.
SPSS outputWhat to inspect
FrequenciesObserved N, expected N, residuals and each category's contribution.
Test StatisticsChi-square, df, asymptotic significance and any footnote.

Assumptions

  • Independent observations.
  • Each participant falls in exactly one category.
  • Expected counts of at least 5 in most categories.

Effect size

Cohen's w can describe discrepancy from expected proportions; phi/Cramér's V definitions for independence tables are not interchangeable with this one-variable design.

Reporting

Report the expected proportions and their rationale, χ²(df, N), p, and any justified effect-size measure.

Use the Results Interpretation Assistant to interpret the values you enter in the context of your research question and project. SPSS output alone does not establish a causal or practically important result.

Pearson correlation

Measures the strength and direction of a straight-line relationship between two numeric variables.

It measures the strength and direction of a straight-line relationship between two quantitative variables.

Why not another test?

  • Simple linear regression: Regression goes further, estimating one variable from the other; correlation treats the two alike.
  • Spearman's rank correlation: Spearman's rank correlation suits ordinal variables, curved but consistently rising or falling relationships, or clearly non-normal data.

SPSS procedure

Bivariate Correlations: Pearson

  1. Analyze
  2. Correlate
  3. Bivariate

IBM documents this path for SPSS Statistics 32. Menu wording, dialog layouts and available options may differ by version, operating system and licensed edition; consult the IBM documentation for the installed version.

Verify this procedure in IBM SPSS Statistics 32 documentation

Variable placement

  • Variables: At least two quantitative variables; each case supplies a paired set of values.

Options and output

  • Select Pearson and the prespecified one- or two-tailed significance test; request confidence intervals if needed.
  • Inspect a scatterplot for linearity and influential outliers.
Pearson correlation: output to inspect Scroll sideways to see every column.
SPSS outputWhat to inspect
CorrelationsPearson correlation, N and significance for the relevant pair.

Assumptions

  • Interval or ratio measurement: The outcome is measured on a numeric scale with equal intervals between values.
  • Independence of observations: Each participant's data are unrelated to every other participant's, and each participant contributes once.
  • Linearity: The relationship between the variables is a straight line.
  • Normality: The outcome is approximately normally distributed within each group.
  • No influential outliers: No single case distorts the result.

Effect size

Pearson's r is itself a standardized association measure; r² is the squared correlation, not a causal proportion explained.

Reporting

Report r(df), p, confidence interval where available, and interpret direction and magnitude in context.

Use the Results Interpretation Assistant to interpret the values you enter in the context of your research question and project. SPSS output alone does not establish a causal or practically important result.

Simple linear regression

Predicts a numeric outcome from one variable.

It estimates a straight-line equation that predicts the outcome from the predictor.

Why not another test?

  • Pearson correlation: Correlation describes how strongly the variables go together but gives no prediction equation.

SPSS procedure

Linear Regression

  1. Analyze
  2. Regression
  3. Linear

IBM documents this path for SPSS Statistics 32. Menu wording, dialog layouts and available options may differ by version, operating system and licensed edition; consult the IBM documentation for the installed version.

Verify this procedure in IBM SPSS Statistics 32 documentation

Variable placement

  • Dependent: One quantitative outcome.
  • Independent(s): One predictor for simple regression.

Options and output

  • Use Statistics for estimates, confidence intervals, model fit and collinearity as relevant.
  • Use Plots and diagnostics to examine residual patterns; select options before inspecting results.
Simple linear regression: output to inspect Scroll sideways to see every column.
SPSS outputWhat to inspect
Model SummaryR, R², adjusted R² and standard error of estimate.
ANOVAModel F, degrees of freedom and significance.
CoefficientsB, standard error, standardized beta, t, significance and confidence interval.

Assumptions

  • Interval or ratio measurement: The outcome is measured on a numeric scale with equal intervals between values.
  • Independence of observations: Each participant's data are unrelated to every other participant's, and each participant contributes once.
  • Linearity: The relationship between the variables is a straight line.
  • Normally distributed residuals: The residuals (the differences between observed and predicted values) are approximately normal.
  • Homoscedasticity: The spread of the residuals is the same at every level of the predicted values.
  • Independent errors: The residuals of any two observations are unrelated, such as over time or in the order data were collected.
  • No influential outliers: No single case distorts the result.

Effect size

R² describes model fit. It is not the same as a standardized mean difference or proof of practical importance.

Reporting

Report model F(df1, df2), p, R²/adjusted R² and the focal coefficient with its confidence interval and p.

Use the Results Interpretation Assistant to interpret the values you enter in the context of your research question and project. SPSS output alone does not establish a causal or practically important result.

Multiple regression

Predicts a numeric outcome from several variables at once, each adjusted for the others.

It estimates each predictor's contribution to the outcome while holding the other predictors constant.

Why not another test?

  • Simple linear regression: Simple regression uses one predictor and can't separate the contributions of related predictors.

SPSS procedure

Linear Regression

  1. Analyze
  2. Regression
  3. Linear

IBM documents this path for SPSS Statistics 32. Menu wording, dialog layouts and available options may differ by version, operating system and licensed edition; consult the IBM documentation for the installed version.

Verify this procedure in IBM SPSS Statistics 32 documentation

Variable placement

  • Dependent: One quantitative outcome.
  • Independent(s): Two or more predictors; categorical predictors require documented contrast/dummy coding.

Options and output

  • Choose entry method and blocks from the prespecified research plan.
  • Inspect collinearity diagnostics, residuals, influence and confidence intervals.
Multiple regression: output to inspect Scroll sideways to see every column.
SPSS outputWhat to inspect
Model SummaryR², adjusted R², change in R² if blocks were specified.
ANOVAOverall model F and significance.
CoefficientsEach B, standard error, beta, t, p and confidence interval.

Assumptions

  • Interval or ratio measurement: The outcome is measured on a numeric scale with equal intervals between values.
  • Independence of observations: Each participant's data are unrelated to every other participant's, and each participant contributes once.
  • Linearity: The relationship between the variables is a straight line.
  • Normally distributed residuals: The residuals (the differences between observed and predicted values) are approximately normal.
  • Homoscedasticity: The spread of the residuals is the same at every level of the predicted values.
  • Independent errors: The residuals of any two observations are unrelated, such as over time or in the order data were collected.
  • No influential outliers: No single case distorts the result.
  • No multicollinearity: The predictors aren't too highly correlated with each other.

Effect size

R² and adjusted R² describe model fit; coefficient magnitudes answer predictor-specific questions. They are distinct quantities.

Reporting

Report overall model F, p, R² and adjusted R², then focal predictor coefficients and confidence intervals.

Use the Results Interpretation Assistant to interpret the values you enter in the context of your research question and project. SPSS output alone does not establish a causal or practically important result.

One-way ANOVA

Compares the means of a numeric outcome across three or more independent groups.

It compares the variation between group means with the variation within groups, in one test across all the groups.

Why not another test?

  • Independent-samples t-test: A t-test for every pair of groups raises the chance of a false positive; ANOVA tests all the groups at once.
  • Repeated measures ANOVA: Repeated measures ANOVA is for the same participants measured several times, not separate groups.

SPSS procedure

One-Way ANOVA

  1. Analyze
  2. Compare Means
  3. One-Way ANOVA

IBM documents this path for SPSS Statistics 32. Menu wording, dialog layouts and available options may differ by version, operating system and licensed edition; consult the IBM documentation for the installed version.

Verify this procedure in IBM SPSS Statistics 32 documentation

Variable placement

  • Dependent List: One or more quantitative outcomes.
  • Factor: One categorical grouping variable with independent groups.

Options and output

  • Request descriptives and homogeneity-of-variance test.
  • Choose planned contrasts or post-hoc comparisons to answer which groups differ; these answer different questions.
  • Request effect-size estimates if available.
One-way ANOVA: output to inspect Scroll sideways to see every column.
SPSS outputWhat to inspect
DescriptivesN, mean, SD and confidence interval per group.
Test of Homogeneity of VariancesLevene statistic and significance.
ANOVABetween/within variation, F, df and significance.
ANOVA Effect SizesThe named effect-size estimate and its interval, if requested.
Post Hoc TestsPairwise comparisons only when selected and justified.

Assumptions

  • Interval or ratio measurement: The outcome is measured on a numeric scale with equal intervals between values.
  • Independence of observations: Each participant's data are unrelated to every other participant's, and each participant contributes once.
  • Normality: The outcome is approximately normally distributed within each group.
  • Homogeneity of variance: The groups being compared have similar variances.
  • No influential outliers: No single case distorts the result.
  • Adequate group sizes: Each group, or combination of groups, has enough participants.

Effect size

Use the effect-size estimate named in SPSS output, commonly eta squared; do not confuse it with partial eta squared.

Reporting

Report group descriptives, F(df1, df2), p, a named effect size and appropriate planned/post-hoc comparisons.

Use the Results Interpretation Assistant to interpret the values you enter in the context of your research question and project. SPSS output alone does not establish a causal or practically important result.

Two-way ANOVA

Compares means across two grouping factors at once, including whether they interact.

It tests each factor's main effect and whether the effect of one factor depends on the other: their interaction.

Why not another test?

  • One-way ANOVA: Two separate one-way ANOVAs can't test whether the factors interact.

SPSS procedure

GLM Univariate: Factorial ANOVA

  1. Analyze
  2. General Linear Model
  3. Univariate

IBM documents this path for SPSS Statistics 32. Menu wording, dialog layouts and available options may differ by version, operating system and licensed edition; consult the IBM documentation for the installed version.

Verify this procedure in IBM SPSS Statistics 32 documentation

Variable placement

  • Dependent Variable: One quantitative outcome.
  • Fixed Factor(s): The categorical factors; include the theoretically relevant interaction in the model.

Options and output

  • Specify the model and sums-of-squares type deliberately.
  • Request descriptive statistics, effect-size estimates, homogeneity tests and profile plots as appropriate.
  • Interpret interaction before main effects when it is relevant.
Two-way ANOVA: output to inspect Scroll sideways to see every column.
SPSS outputWhat to inspect
Between-Subjects FactorsFactor levels and case counts.
Descriptive StatisticsMeans, SDs and counts for cells.
Levene's Test of Equality of Error VariancesHomogeneity evidence.
Tests of Between-Subjects EffectsEach factor and interaction: F, df, p, partial eta squared.
Estimated Marginal MeansAdjusted means for comparisons/plots when requested.

Assumptions

  • Interval or ratio measurement: The outcome is measured on a numeric scale with equal intervals between values.
  • Independence of observations: Each participant's data are unrelated to every other participant's, and each participant contributes once.
  • Normality: The outcome is approximately normally distributed within each group.
  • Homogeneity of variance: The groups being compared have similar variances.
  • No influential outliers: No single case distorts the result.
  • Adequate group sizes: Each group, or combination of groups, has enough participants.

Effect size

Partial eta squared is commonly listed for each model effect; report which effect it describes.

Reporting

Report each factor and interaction F(df1, df2), p and partial eta squared; explain follow-up comparisons and simple effects.

Use the Results Interpretation Assistant to interpret the values you enter in the context of your research question and project. SPSS output alone does not establish a causal or practically important result.

ANCOVA

Compares group means on a numeric outcome after adjusting for a numeric covariate, such as a control variable or a pretest score.

It compares group means adjusted for a covariate that also relates to the outcome, which can account for initial differences and reduce unexplained variation.

Why not another test?

  • One-way ANOVA: One-way ANOVA compares unadjusted means, leaving out the covariate.

SPSS procedure

GLM Univariate: ANCOVA

  1. Analyze
  2. General Linear Model
  3. Univariate

IBM documents this path for SPSS Statistics 32. Menu wording, dialog layouts and available options may differ by version, operating system and licensed edition; consult the IBM documentation for the installed version.

Verify this procedure in IBM SPSS Statistics 32 documentation

Variable placement

  • Dependent Variable: One quantitative outcome.
  • Fixed Factor(s): Categorical group variable(s).
  • Covariate(s): Quantitative covariate measured and justified for adjustment.

Options and output

  • Specify the covariate and group model before analysis.
  • Check homogeneity of regression slopes; if the covariate-by-factor interaction is retained, interpretation changes.
  • Request estimated marginal means and effect-size estimates as appropriate.
ANCOVA: output to inspect Scroll sideways to see every column.
SPSS outputWhat to inspect
Descriptive StatisticsUnadjusted group descriptives.
Levene's Test of Equality of Error VariancesHomogeneity evidence.
Tests of Between-Subjects EffectsCovariate and adjusted factor effects, F, df, p and partial eta squared.
Estimated Marginal MeansAdjusted group means at the specified covariate value.

Assumptions

  • Interval or ratio measurement: The outcome is measured on a numeric scale with equal intervals between values.
  • Independence of observations: Each participant's data are unrelated to every other participant's, and each participant contributes once.
  • Normally distributed residuals: The residuals (the differences between observed and predicted values) are approximately normal.
  • Homogeneity of variance: The groups being compared have similar variances.
  • Linearity: The relationship between the variables is a straight line.
  • Homogeneity of regression slopes: The covariate relates to the outcome in the same way in every group.
  • Covariate independent of the grouping: The covariate isn't affected by group membership, usually because it is measured before the intervention.
  • No influential outliers: No single case distorts the result.

Effect size

Partial eta squared for the adjusted factor effect is often reported; identify the effect and model used.

Reporting

Report unadjusted and adjusted means, covariate handling, the adjusted group F(df1, df2), p, partial eta squared and confidence intervals where available.

Use the Results Interpretation Assistant to interpret the values you enter in the context of your research question and project. SPSS output alone does not establish a causal or practically important result.

Check assumptions with the existing Assumption Checker

The Statistical Assumption Checker owns the assumption definitions, design-aware checks, thresholds and remedies. Use it to prepare a checklist, then inspect the relevant data and model diagnostics in SPSS. Independence comes from the sampling/design; a menu option cannot repair dependent observations. For a paired t-test, examine the differences. For regression and GLM models, inspect residuals and the model structure.

  • Normality is not a universal pass/fail switch; consider the relevant residuals or paired differences, plots, sample size and robustness.
  • Homogeneity tests such as Levene's are evidence to consider, not an automatic command to change tests.
  • Outlier rules should be justified by data quality and design; do not remove valid cases solely to obtain a preferred p-value.
  • If assumptions are questionable, consult the method's alternatives and supervisor; record the decision and sensitivity checks.
Roughly normalMost scores sit in the middle, tailing off evenly on both sides. Bar heights from left to right: 1, 3, 6, 9, 6, 3, 1.

Roughly normal

Most scores sit in the middle, tailing off evenly on both sides.

Skewed to the rightMost scores are low, with a long tail of a few high scores. Bar heights from left to right: 9, 8, 5, 3, 2, 1, 1.

Skewed to the right

Most scores are low, with a long tail of a few high scores.

Roughly normal and clearly skewed distributionsScores from low (left) to high (right); bar height is the number of participants.Illustrative counts, not data from a study. Real data are judged from plots and statistics together, as the Statistical Assumption Checker explains.
Similar spreadBoth groups' scores are spread over about 20 points. Group A: 40, 45, 50, 55, 60. Group B: 42, 47, 52, 57, 62.Group AGroup B2575

Similar spread

Both groups' scores are spread over about 20 points.

Very different spreadGroup A's scores lie within 4 points of each other; Group B's are spread over 40 points. Group A: 48, 49, 50, 51, 52. Group B: 30, 40, 50, 60, 70.Group AGroup B2575

Very different spread

Group A's scores lie within 4 points of each other; Group B's are spread over 40 points.

Similar and very different spreads in two groupsIllustrative values, not data from a study. Homogeneity of variance asks for spreads like the first pair; Welch's versions of the tests allow spreads like the second.

Effect size, statistical significance and practical importance differ

A p-value is evidence relative to a specified null model; an effect size describes a chosen measure of magnitude; practical importance depends on consequences, context, measurement and uncertainty. None implies the others (Wasserstein & Lazar, 2016). Conventional magnitude thresholds are context-bound guides, not universal laws (Cohen, 1988). For t-tests, name the standardizer; for paired data, d_z and d_av use different denominators (Hedges, 1981; Lakens, 2013). For ANOVA, distinguish eta squared from partial eta squared. For contingency tables, use a measure suited to the table design.

  • Mean

    x̄ = Σx ÷ n

    Where

    x̄
    the sample mean
    Σx
    the sum of all the values
    n
    the number of values

    Add every value and divide by how many there are.

  • Sample standard deviation

    s = √[ Σ(x − x̄)² ÷ (n − 1) ]

    Where

    s
    the sample standard deviation
    x
    each value
    x̄
    the sample mean
    n
    the number of values

    The typical distance of values from the mean. Dividing by n − 1 rather than n makes it a better estimate of the population's spread.

  • The idea behind every t-test

    t = difference ÷ standard error of the difference

    Where

    difference
    the difference being tested, such as between two group means
    standard error
    how much that difference would vary from sample to sample by chance

    A t value compares the difference found with the variation expected by chance. The further t is from zero, the less the difference looks like chance alone.

  • One-sample t

    t = (x̄ − μ₀) ÷ (s ÷ √n), with n − 1 degrees of freedom

    Where

    x̄
    the sample mean
    μ₀
    the value the mean is compared with, stated in advance
    s
    the sample standard deviation
    n
    the number of participants

    How far the sample mean lies from the stated value, measured in standard errors.

  • Paired-samples t

    t = d̄ ÷ (s_d ÷ √n), with n − 1 degrees of freedom

    Where

    d̄
    the mean of the differences between each participant's two measurements
    s_d
    the standard deviation of those differences
    n
    the number of pairs

    A paired t-test is a one-sample t-test on the differences, comparing their mean with zero.

  • Expected count in a cross-tabulation

    E = (row total × column total) ÷ N

    Where

    E
    the count expected in a cell if the two variables were unrelated
    N
    the total number of participants

    If the variables were unrelated, each cell would hold its row's share of its column's total.

  • Chi-square statistic

    χ² = Σ (O − E)² ÷ E

    Where

    χ²
    the chi-square statistic
    O
    the observed count in a cell or category
    E
    the expected count in the same cell or category
    Σ
    add the result for every cell or category

    The larger the gaps between observed and expected counts, relative to the expected counts, the larger χ².

  • Simple linear regression

    Y = β₀ + β₁X + ε

    Where

    Y
    the outcome
    X
    the predictor
    β₀
    the intercept, the predicted outcome when X is zero
    β₁
    the slope, the change in the predicted outcome for each one-unit increase in X
    ε
    the error, what the line doesn't explain for each participant

    The outcome is modelled as a straight line in the predictor, plus what the line leaves unexplained.

  • Multiple linear regression

    Y = β₀ + β₁X₁ + β₂X₂ + … + βₖXₖ + ε

    Where

    Y
    the outcome
    X₁ … Xₖ
    the k predictors
    β₀
    the intercept
    β₁ … βₖ
    each predictor's slope, holding the other predictors constant
    ε
    the error

    Each slope estimates a predictor's contribution while the other predictors are held constant.

  • The F ratio in ANOVA

    F = variance between groups ÷ variance within groups

    Where

    variance between groups (mean square between)
    how far the group means spread around the overall mean
    variance within groups (mean square within)
    how far participants spread around their own group's mean

    When the group means differ by much more than participants differ within groups, F is large.

The Effect Size Calculator shows inputs, formulas and substitutions. It does not calculate significance or declare practical importance. IBM SPSS Statistics 32 can estimate effect sizes in its one-sample and independent/paired t-test procedures and one-way ANOVA when the relevant effect-size option is selected; available standardizers and tables differ by procedure.

Find the value, then interpret and report it

Read the named output table and row for the effect you planned. Record the correct test row (for example, the variance row justified by the assumptions for an independent t-test), degrees of freedom, p-value, estimate, confidence interval and effect size. For GLM, distinguish the factor, interaction, covariate and error rows. For regression, distinguish model fit from an individual predictor's coefficient. For crosstabs, inspect expected counts and the correct association statistic.

The Results Interpretation Assistant validates and interprets the numbers you enter, linking them to the project where possible. It does not read an output file or recompute raw data. An APA-style result should identify the analysis, statistic and degrees of freedom where applicable, p, effect-size measure and relevant interval; accompany it with the design-specific substantive explanation and limitations.

Work through synthetic examples

The datasets below are fixed and invented for teaching. They show research questions, variable roles, data structure, candidate method and summaries. They are not empirical findings, are too small to support strong inferential conclusions, and do not contain fabricated SPSS p-values or completed APA results.

Research questionIs mean job satisfaction different between public and private bank employees?

Business research

Variables

  • Bank type: Grouping variable (independent variable), nominal level. Two categories: public and private.
  • Job satisfaction: Outcome (dependent variable), interval level. A scale score from ten rating items, commonly treated as interval.

Groups

Two groups: public and private bank employees.

Structure

Independent: each employee works in one type of bank only.

Grouping variable (independent variable)Bank type
  • Public banks
  • Private banks
Outcome (dependent variable)Job satisfaction
Two independent groups compared on one outcomeA grouping variable, bank type, splits participants into two separate groups, public and private; their mean job satisfaction is compared.

A candidate test

Independent-samples t-test. A quantitative outcome is compared between two independent groups, which is the situation the independent-samples t-test is built for.

Assumptions to check

  • Interval or ratio measurement
  • Independence of observations
  • Normality
  • Homogeneity of variance
  • No influential outliers
Job satisfaction scores out of 50 (invented for illustration) Scroll sideways to see every column.
EmployeeBank typeSatisfaction
1Public38
2Public34
3Public40
4Public36
5Private32
6Private35
7Private30
8Private31

Worked from the data

  • Public: mean = (38 + 34 + 40 + 36) ÷ 4 = 148 ÷ 4 = 37.0.
  • Private: mean = (32 + 35 + 30 + 31) ÷ 4 = 128 ÷ 4 = 32.0.
  • The sample means differ by 5.0 points. With four employees per group this is an illustration only; the test weighs the gap against the spread within each group.

What the result would tell you

The test asks whether the gap between the group means is larger than chance would usually produce. Report the effect size as well: a clear difference can still be small in practice.

Research questionDid students' mean scores change after training?

Education research

Variables

  • Score before training: First measurement, interval level. A test score out of 100.
  • Score after training: Second measurement, same students, interval level. The same test, taken again.

Groups

One group of students, measured twice.

Structure

Paired: every “after” score belongs to the same student as one “before” score.

First measurementScore before training
Second measurement, same participantsScore after training
The same participants measured twiceEach participant's score before training is compared with their own score after training.

A candidate test

Paired-samples t-test. The same students are measured twice on a quantitative outcome, so the paired-samples t-test analyses each student's change.

Assumptions to check

  • Interval or ratio measurement
  • Paired observations
  • Normally distributed differences
  • No influential outliers
Test scores before and after training (invented for illustration) Scroll sideways to see every column.
StudentBeforeAfterDifference
162686
255605
370744
458591
565716

Worked from the data

  • Mean before = 62.0; mean after = 66.4.
  • Mean difference d̄ = (6 + 5 + 4 + 1 + 6) ÷ 5 = 4.4, with s_d = 2.07, so t = 4.4 ÷ (2.07 ÷ √5) = 4.74 with 4 degrees of freedom.

What the result would tell you

The test asks whether the mean change is further from zero than chance would usually produce. Without a comparison group it can't show that the training caused the change: practice, time or other events may explain it.

Research questionIs study time associated with examination score?

Education research

Variables

  • Study time: First variable, ratio level. Hours of study per week.
  • Examination score: Second variable, interval level. A score out of 100.

Groups

One group of students, each with a value on both variables.

Structure

Each student contributes one pair of values; no variable is treated as the outcome.

First variable (quantitative)Study time
Second variable (quantitative)Exam score
Two quantitative variables examined togetherStudy time and exam score are examined together, with no variable treated as the outcome.

A candidate test

Pearson correlation. Two quantitative variables are examined together for a straight-line relationship, which Pearson's correlation measures.

Assumptions to check

  • Interval or ratio measurement
  • Independence of observations
  • Linearity
  • Normality
  • No influential outliers
Study time and exam score for six students (invented for illustration) Scroll sideways to see every column.
StudentStudy hoursExam score
1255
2456
3563
4764
5872
61074

Worked from the data

  • Pearson's r = 0.96 for these six illustrative students: a strong positive straight-line relationship in this sample.

What the result would tell you

A positive correlation means that students who study more tend to score higher. It doesn't show that studying causes higher scores: ability or motivation could affect both.

Research questionDo mean scores differ across three teaching methods?

Education research

Variables

  • Teaching method: Grouping variable (factor), nominal level. Lecture, discussion or online.
  • Exam score: Outcome (dependent variable), interval level. A score out of 100.

Groups

Three groups: lecture, discussion and online.

Structure

Independent: each student is taught by one method only.

Grouping variable (factor)Teaching method
  • Lecture
  • Discussion
  • Online
Outcome (dependent variable)Exam score
Three or more independent groups compared on one outcomeA grouping variable, teaching method, forms three separate groups: lecture, discussion and online. Their mean exam scores are compared.

A candidate test

One-way ANOVA. A quantitative outcome is compared across three independent groups in one test, which is what one-way ANOVA does.

Assumptions to check

  • Interval or ratio measurement
  • Independence of observations
  • Normality
  • Homogeneity of variance
  • No influential outliers
  • Adequate group sizes
Exam scores under three teaching methods (invented for illustration) Scroll sideways to see every column.
StudentMethodScore
1Lecture65
2Lecture70
3Lecture60
4Discussion75
5Discussion72
6Discussion78
7Online68
8Online64
9Online66

Worked from the data

  • Lecture: mean = (65 + 70 + 60) ÷ 3 = 195 ÷ 3 = 65.0.
  • Discussion: mean = (75 + 72 + 78) ÷ 3 = 225 ÷ 3 = 75.0.
  • Online: mean = (68 + 64 + 66) ÷ 3 = 198 ÷ 3 = 66.0.
  • Mean square between = 91.0; mean square within = 12.67; F = 91.0 ÷ 12.67 = 7.18, with 2 and 6 degrees of freedom.

What the result would tell you

A large F says the group means differ more than the variation within groups would lead you to expect. It doesn't say which groups differ: post hoc tests or planned comparisons answer that.

Research questionIs employment status associated with gender?

Social science research

Variables

  • Gender: First categorical variable, nominal level. Female or male, as recorded in this survey.
  • Employment status: Second categorical variable, nominal level. Employed or unemployed.

Groups

Two categories of each variable, making a 2 × 2 table.

Structure

Independent: each respondent is counted once, in one cell.

First variable (categorical)Gender
Second variable (categorical)Employment status
Two categorical variables examined togetherGender and employment status, both categorical, are cross-tabulated to see whether they are associated.

A candidate test

Chi-square test of independence. Both variables are categories, so the question is whether the counts in the table depart from what unrelated variables would give.

Assumptions to check

  • Categorical variables
  • Independence of observations
  • Adequate expected counts
Observed counts, with expected counts in brackets (invented for illustration) Scroll sideways to see every column.
GenderEmployedUnemployedTotal
Female42 (45)18 (15)60
Male48 (45)12 (15)60
Total9030120

Worked from the data

  • Expected count for employed women = (60 × 90) ÷ 120 = 45; the other cells follow the same way.
  • χ² = (42 − 45)² ÷ 45 + (18 − 15)² ÷ 15 + (48 − 45)² ÷ 45 + (12 − 15)² ÷ 15 = 1.60, with 1 degree of freedom.

What the result would tell you

The test asks whether the pattern of counts differs from independence by more than chance would usually produce. It says nothing about cause, and a clear association can still be weak; Cramér's V describes its strength.

Research questionDo customers choose the bank's four service channels equally often?

Business research

Variables

  • Service channel chosen: Categorical variable, nominal level. Branch, mobile app, ATM or internet banking.

Groups

Four categories, compared with equal expected shares.

Structure

Independent: each customer's most recent transaction is counted once.

Categorical variable (observed counts)Service channel chosen
Expected counts (stated in advance)Equal shares for every channel
One categorical variable compared with expected sharesThe counts of customers choosing each service channel are compared with the counts expected if every channel were chosen equally often.

A candidate test

Chi-square goodness-of-fit test. One categorical variable is compared with shares stated in advance, which is what the goodness-of-fit test does.

Assumptions to check

  • Independent observations.
  • Each participant falls in exactly one category.
  • Expected counts of at least 5 in most categories.
Channel used by 120 customers (invented for illustration) Scroll sideways to see every column.
ChannelObservedExpected
Branch3830
Mobile app4230
ATM2230
Internet banking1830

Worked from the data

  • Equal shares give 120 ÷ 4 = 30 expected customers per channel.
  • χ² = Σ (O − E)² ÷ E = 13.87, with 3 degrees of freedom (four categories minus one).

What the result would tell you

The test asks whether the counts depart from equal shares by more than chance would usually produce. It doesn't say which channels differ, or why; look at the gap between observed and expected counts in each category.

  • Employee satisfaction across two bank types: identify the outcome, independent grouping factor and independent-samples t-test structure.
  • The same participants before and after training: identify pairs and why the analysis concerns within-person differences.
  • Study hours and exam score: decide whether the question is symmetric association (correlation) or prediction (regression).
  • Exam scores across three teaching groups: explain why one overall ANOVA precedes justified pairwise follow-up.
  • Observed customer service-channel counts: distinguish goodness-of-fit against stated shares from independence in a two-variable crosstab.

Keep a reproducible analysis record

SPSS syntax is a record of commands that can be saved and rerun. For example, `FREQUENCIES VARIABLES=department.` is a short syntax command for a frequency table; inspect the pasted command and adapt variable names to your file. Preserve syntax with the input data, output, codebook and decision log. A reproducible record explains sample exclusions, coding, transformations, model specification, assumption checks, output values and reporting choices. Syntax is not a substitute for understanding the analysis.

A compact reproducible project folder Scroll sideways to see every column.
ArtifactRecord
DataUnmodified source and clearly named analysis copy; describe provenance and exclusions.
CodebookVariable names/labels, category codes, missing values, units and measurement.
SyntaxImports, cleaning, recodes, computed scores, procedure, options and software version.
OutputTables and diagnostics used; keep enough context to trace reported values.
Decision logResearch question, chosen method, assumptions, effect-size convention and justified deviations.
ReportStatistic, df, p, effect size, interval, interpretation and limitations.
  1. Research question and design
  2. Variables and data preparation
  3. Descriptive checks
  4. Select a test with the Statistical Test Finder
  5. Run the mapped procedure in SPSS
  6. Review assumptions with the Assumption Checker
  7. Calculate a suitable effect size
  8. Read output and interpret the reported values
  9. Write and preserve the analysis report

Common mistakes and limits

  • Choosing a test because it is familiar or because the software menu makes it easy, rather than because the question and design support it.
  • Treating independent groups as paired, or paired measurements as independent.
  • Confusing one-variable goodness-of-fit chi-square with a two-variable test of independence.
  • Ignoring data coding, duplicate cases, missingness, distributions, expected counts or residual diagnostics.
  • Changing the analysis after seeing results without a prespecified methodological reason.
  • Reporting only p, treating p < .05 as practical importance, or treating a large effect-size label as statistical significance.
  • Copying output tables without identifying which row answers the research question or acknowledging multiple comparisons.
  • Treating correlation or regression as proof of causation.

ResearchKit supports methodological reasoning; it cannot inspect your SPSS dataset, verify its provenance, certify assumptions, choose among all valid models, or replace supervisor/statistician judgment. When your design includes clustering, survey weights, substantial missingness, complex sampling, repeated-factor designs, or methods outside the supported catalogue, seek specialist guidance.

References and official SPSS documentation

Operational menu paths and procedure descriptions link directly to IBM SPSS Statistics 32 documentation. Methodological references support the statistical explanations and effect-size distinctions.

  • Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed.). Lawrence Erlbaum Associates.
  • Field, A. (2018). Discovering statistics using IBM SPSS statistics (5th ed.). SAGE.
  • Hedges, L. V. (1981). Distribution theory for Glass's estimator of effect size and related estimators. Journal of Educational Statistics, 6(2), 107–128. https://doi.org/10.3102/10769986006002107 (external link)
  • Howell, D. C. (2013). Statistical methods for psychology (8th ed.). Wadsworth, Cengage Learning.
  • Lakens, D. (2013). Calculating and reporting effect sizes to facilitate cumulative science: A practical primer for t-tests and ANOVAs. Frontiers in Psychology, 4, Article 863. https://doi.org/10.3389/fpsyg.2013.00863 (external link)
  • Wasserstein, R. L., & Lazar, N. A. (2016). The ASA statement on p-values: Context, process, and purpose. The American Statistician, 70(2), 129–133. https://doi.org/10.1080/00031305.2016.1154108 (external link)

Frequently asked questions

Does the SPSS Research Lab choose my statistical test?

No. The Statistical Test Finder owns that decision support. The Lab maps an already selected analysis method to a documented SPSS procedure.

Does SPSS install with ResearchKit?

No. SPSS is IBM software. Obtain it through IBM or your institution and follow IBM's current licensing and installation instructions.

Does a significant p-value mean the effect matters?

No. Statistical significance, effect magnitude and practical importance answer different questions. Interpret them with design, measurement, context and uncertainty.

Does the Lab save or upload my data?

No. It does not accept SPSS data files or save procedure state. If you use the ResearchKit workspace, its existing browser-only storage behavior applies.

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