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.
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.
- Research question and design
- Variables and data preparation
- Descriptive checks
- Select a test with the Statistical Test Finder
- Run the mapped procedure in SPSS
- Review assumptions with the Assumption Checker
- Calculate a suitable effect size
- Read output and interpret the reported values
- 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.
| Window or file | Purpose |
|---|---|
| Data Editor: Data View | Rows are cases; columns are variables and their recorded values. |
| Data Editor: Variable View | Define 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.
| Question | Variable roles | Structure to record |
|---|---|---|
| Do two groups differ in a score? | Quantitative outcome; categorical grouping variable | Separate participants or the same/matched participants? |
| Are two measurements associated? | Two variables; neither is inherently the outcome for correlation | One pair of values per case; inspect the form of association |
| Can predictors estimate an outcome? | Outcome plus one or more predictors | Predictor coding, model specification and residual diagnostics |
| Do category counts match stated proportions? | One categorical variable and expected proportions | Observed independent counts; expected proportions justified in advance |
| Are two categories associated? | Two categorical variables | One observation per case in a cross-tabulation cell |
- Public banks
- Private banks
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.
| Variable | Type / level | Example documentation |
|---|---|---|
| department | Categorical / nominal | 1 = Operations; 2 = Finance; 3 = Marketing. Codes are local to this example. |
| education | Categorical / ordinal | 1 = Secondary; 2 = Bachelor's; 3 = Master's; 4 = MPhil; 5 = PhD. Verify order and labels for the study. |
| agreement_item | Ordered response / ordinal | 1 = 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.
| Employee | Days |
|---|---|
| 1 | 2 |
| 2 | 3 |
| 3 | 3 |
| 4 | 3 |
| 5 | 4 |
| 6 | 5 |
| 7 | 5 |
| 8 | 6 |
| 9 | 14 |
| Statistic | Value | Working | What it tells you |
|---|---|---|---|
| Mean | 5.0 | (2 + 3 + 3 + 3 + 4 + 5 + 5 + 6 + 14) ÷ 9 = 45 ÷ 9 | The average, pulled upwards by the one employee with 14 days. |
| Median | 4.0 | The 5th of the 9 values in order | The middle employee attended 4 days: half attended fewer or the same, half the same or more. |
| Mode | 3 | 3 appears three times, more than any other value | The most common number of days. |
| Standard deviation | 3.61 | √[ 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.
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 candidate test | Research purpose | Outcome | Groups or variables | Structure | Key assumptions | Alternative or related method |
|---|---|---|---|---|---|---|
| One-sample t-test | Does 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. |
| One-sample Wilcoxon signed-rank test |
| Independent-samples t-test | Do 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. |
| Mann–Whitney U test |
| Paired-samples t-test | Does 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. |
| Wilcoxon signed-rank test |
| One-way ANOVA | Do 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. |
| Kruskal–Wallis test |
| Two-way ANOVA | Do 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. |
| Aligned rank transform ANOVA |
| ANCOVA | Do 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. |
| Quade's rank analysis of covariance |
| Chi-square test of independence | Are 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. |
| Fisher's exact test |
| Chi-square goodness-of-fit test | Do 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. |
| Chi-square test of independence |
| Pearson correlation | Do 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. |
| Spearman's rank correlation |
| Simple linear regression | How 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. |
| Spearman's rank correlation |
| Multiple regression | How 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. |
| Robust (heteroscedasticity-consistent) standard errors |
The table scrolls sideways on narrow screens.
| Situation | Common parametric method | Possible rank/count method | Decision point |
|---|---|---|---|
| Two independent groups, ordered or quantitative outcome | Independent-samples t-test | Mann–Whitney U | Estimand, measurement, distribution, design and robustness |
| Two paired measurements | Paired-samples t-test | Wilcoxon signed-rank | Analyze pairing; for t, consider the distribution of differences |
| Three or more independent groups | One-way ANOVA | Kruskal–Wallis | A global test does not identify which groups differ |
| Two quantitative measurements | Pearson correlation | Spearman rank correlation | Linear 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
- Analyze
- Compare Means
- 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 documentationVariable 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.
| SPSS output | What to inspect |
|---|---|
| One-Sample Statistics | N, mean and standard deviation. |
| One-Sample Test | Test 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
- Analyze
- Compare Means
- 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 documentationVariable 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.
| SPSS output | What to inspect |
|---|---|
| Group Statistics | Group N, mean and standard deviation. |
| Independent Samples Test | Levene 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
- Analyze
- Compare Means
- 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 documentationVariable 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.
| SPSS output | What to inspect |
|---|---|
| Paired Samples Statistics | N, mean and standard deviation for each measurement. |
| Paired Samples Correlations | The correlation between the paired measurements; it is not the change test. |
| Paired Samples Test | 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.
- 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
- Analyze
- Descriptive Statistics
- Crosstabs
- Statistics
- 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 documentationVariable 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.
| SPSS output | What to inspect |
|---|---|
| Crosstabulation | Observed counts, expected counts and the percentages appropriate to the question. |
| Chi-Square Tests | Pearson 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)
- Analyze
- Nonparametric Tests
- Legacy Dialogs
- 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 documentationVariable 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.
| SPSS output | What to inspect |
|---|---|
| Frequencies | Observed N, expected N, residuals and each category's contribution. |
| Test Statistics | Chi-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
- Analyze
- Correlate
- 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 documentationVariable 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.
| SPSS output | What to inspect |
|---|---|
| Correlations | Pearson 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
- Analyze
- Regression
- 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 documentationVariable 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.
| SPSS output | What to inspect |
|---|---|
| Model Summary | R, R², adjusted R² and standard error of estimate. |
| ANOVA | Model F, degrees of freedom and significance. |
| Coefficients | B, 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
- Analyze
- Regression
- 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 documentationVariable 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.
| SPSS output | What to inspect |
|---|---|
| Model Summary | R², adjusted R², change in R² if blocks were specified. |
| ANOVA | Overall model F and significance. |
| Coefficients | Each 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
- Analyze
- Compare Means
- 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 documentationVariable 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.
| SPSS output | What to inspect |
|---|---|
| Descriptives | N, mean, SD and confidence interval per group. |
| Test of Homogeneity of Variances | Levene statistic and significance. |
| ANOVA | Between/within variation, F, df and significance. |
| ANOVA Effect Sizes | The named effect-size estimate and its interval, if requested. |
| Post Hoc Tests | Pairwise 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
- Analyze
- General Linear Model
- 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 documentationVariable 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.
| SPSS output | What to inspect |
|---|---|
| Between-Subjects Factors | Factor levels and case counts. |
| Descriptive Statistics | Means, SDs and counts for cells. |
| Levene's Test of Equality of Error Variances | Homogeneity evidence. |
| Tests of Between-Subjects Effects | Each factor and interaction: F, df, p, partial eta squared. |
| Estimated Marginal Means | Adjusted 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
- Analyze
- General Linear Model
- 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 documentationVariable 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.
| SPSS output | What to inspect |
|---|---|
| Descriptive Statistics | Unadjusted group descriptives. |
| Levene's Test of Equality of Error Variances | Homogeneity evidence. |
| Tests of Between-Subjects Effects | Covariate and adjusted factor effects, F, df, p and partial eta squared. |
| Estimated Marginal Means | Adjusted 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 normal
Most scores sit in the middle, tailing off evenly on both sides.
Skewed to the right
Most scores are low, with a long tail of a few high scores.
Similar spread
Both groups' scores are spread over about 20 points.
Very different spread
Group A's scores lie within 4 points of each other; Group B's are spread over 40 points.
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 researchVariables
- 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.
- Public banks
- Private banks
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
| Employee | Bank type | Satisfaction |
|---|---|---|
| 1 | Public | 38 |
| 2 | Public | 34 |
| 3 | Public | 40 |
| 4 | Public | 36 |
| 5 | Private | 32 |
| 6 | Private | 35 |
| 7 | Private | 30 |
| 8 | Private | 31 |
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 researchVariables
- 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.
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
| Student | Before | After | Difference |
|---|---|---|---|
| 1 | 62 | 68 | 6 |
| 2 | 55 | 60 | 5 |
| 3 | 70 | 74 | 4 |
| 4 | 58 | 59 | 1 |
| 5 | 65 | 71 | 6 |
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 researchVariables
- 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.
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
| Student | Study hours | Exam score |
|---|---|---|
| 1 | 2 | 55 |
| 2 | 4 | 56 |
| 3 | 5 | 63 |
| 4 | 7 | 64 |
| 5 | 8 | 72 |
| 6 | 10 | 74 |
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 researchVariables
- 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.
- Lecture
- Discussion
- Online
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
| Student | Method | Score |
|---|---|---|
| 1 | Lecture | 65 |
| 2 | Lecture | 70 |
| 3 | Lecture | 60 |
| 4 | Discussion | 75 |
| 5 | Discussion | 72 |
| 6 | Discussion | 78 |
| 7 | Online | 68 |
| 8 | Online | 64 |
| 9 | Online | 66 |
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 researchVariables
- 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.
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
| Gender | Employed | Unemployed | Total |
|---|---|---|---|
| Female | 42 (45) | 18 (15) | 60 |
| Male | 48 (45) | 12 (15) | 60 |
| Total | 90 | 30 | 120 |
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 researchVariables
- 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.
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 | Observed | Expected |
|---|---|---|
| Branch | 38 | 30 |
| Mobile app | 42 | 30 |
| ATM | 22 | 30 |
| Internet banking | 18 | 30 |
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.
| Artifact | Record |
|---|---|
| Data | Unmodified source and clearly named analysis copy; describe provenance and exclusions. |
| Codebook | Variable names/labels, category codes, missing values, units and measurement. |
| Syntax | Imports, cleaning, recodes, computed scores, procedure, options and software version. |
| Output | Tables and diagnostics used; keep enough context to trace reported values. |
| Decision log | Research question, chosen method, assumptions, effect-size convention and justified deviations. |
| Report | Statistic, df, p, effect size, interval, interpretation and limitations. |
- Research question and design
- Variables and data preparation
- Descriptive checks
- Select a test with the Statistical Test Finder
- Run the mapped procedure in SPSS
- Review assumptions with the Assumption Checker
- Calculate a suitable effect size
- Read output and interpret the reported values
- 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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