The centerInteractions parameter
What it does
TRUE builds an interaction a*b from mean-centered values: (a − mean of a) · (b − mean of b), the means over the rows of the model. Only the product is centered: a, b and the other predictors stay as they are.
B, SE and p of a*b, R Square and F do not change. The B of a becomes its effect at the mean of b (without centering — its effect where b is 0, which may be outside the scale), and the VIF of the product drops.
A step with an interaction says so under its coefficients: "Interaction terms use mean-centered values: …". A step without an interaction does not change.
Empty — the value from Settings (FALSE by default); the setting applies to STATS_LINEAR, STATS_LOGISTIC and STATS_BOOTSTRAP. TRUE, 1 or their text turn it on; FALSE, 0 or their text turn it off; anything else is an error: centerInteractions must be TRUE or FALSE (or 1, 0), got "yes".
Values
Optional; default FALSE.
Should be TRUE or FALSE
In plain words
A teacher wanted to know whether the link between hours of study and score is different at different ages, so she added a column made from hours and age together. With centerInteractions FALSE, the number for hours came out 8 points per hour, but that is for a student aged 0, and nobody is. With TRUE it came out 3 points per hour, which is for a student of the average age, 15. The number for the new column itself stayed the same either way. So with TRUE the number for hours is one she can read and tell her students.
Where you use it
STATS_LINEAR— Multiple linear regression (OLS) with hierarchical steps separated by | and interactions a*b.STATS_LOGISTIC— Binary logistic regression with optional ridge regularization (lambda >= 0).STATS_BOOTSTRAP— Bootstrap confidence intervals for regression via resampling.
Examples
TRUE— a*b from centered a and bFALSE— a*b from the raw values
Get it in your sheet
ALS Stats is a free add-on for Google Sheets™.
Install ALS Stats from Google Workspace Marketplace (opens in a new tab)