Moderation
Test whether one predictor’s slope depends on a second predictor.
When to use it
Use moderation when you think the slope of X changes across levels of M. For example: does an extra study hour buy more exam points when anxiety is low than when anxiety is high? The test is the product term, hours × anxiety.
Assumptions
Same straight-line model as linear regression, plus the product term. Tensr centers the predictors by default before building that product, so the hours slope is the slope at average anxiety.
Running it in Tensr
Options
Prop
Type
Reading the output
Hours predicting exam score, with practice quizzes as the moderator. Practice was built with no link to the slope, so the interaction is the result to read.
| Term | B | SE | p |
|---|---|---|---|
| Intercept | 71.372 | 0.815 | < .001 |
| hours | 2.108 | 0.706 | .004 |
| practice | -0.247 | 0.851 | .772 |
| hours × practice | -0.307 | 0.655 | .641 |
| Moderator level | Slope |
|---|---|
| Low M (−1 SD) | 2.405 |
| Mean M | 2.108 |
| High M (+1 SD) | 1.811 |
The interaction between hours and practice is not statistically significant at the 95% level, suggesting moderation is not supported. The primary result is not significant (p = .641). This is not large enough to treat the comparison this page is about as a reliable association. The result is non-significant: the data are still compatible with no effect. Metrics: R² = 0.11; Adj R² = 0.081; F = 3.776; p (model) = .013; p (interaction) = .641.
Reporting (APA 7)
The interaction between hours and practice is not statistically significant at the 95% level, suggesting moderation is not supported. This result is not significant (p = .641). Report the estimate with that p, and do not describe the pattern as a reliable effect.
Coming from SPSS
Analyze → Regression → Moderation.
SPSS does not ship a single Moderation dialog in the base menus. The usual path is Linear Regression with a computed product term. Tensr builds that product and the simple slopes.
Related
Entering hours and anxiety without a product term is linear regression.