With gratitude to Kit Baum for keeping up the SSC archive, I am pleased to announce the release of the package icalc through the SSC archive.

ICALC stands for Interaction CALCulator. It is a toolkit of five commands to aid in the interpretation and reporting of interaction effects in Generalized Linear models. Effects can be reported in the original model metric, the as-estimated metric, or when relevant as factor changes and/or marginal changes. See Kaufman (2018) for a discussion of the principles of interpreting interaction effects as well as detailed explanations and step-by-step examples of using the ICALC commands.

intspec is a setup command which defines the focal and moderating variables and the order and form of the interaction

gfi produces algebraic expression for the effect of a focal variable as it changes with the moderator(s)

sigreg creates a table showing the focal variable’s effect and statistical significance as it varies across the values of the moderating predictor(s)

effdisp produces a variety of types of plots (line, dropline errorbar, contour) displaying the value of the focal variable's effect on the observed or "modeled" outcome as it varies with the values of its moderator(s)

outdisp produces tables, bar charts, scatterplots or contour plots displaying the outcome’s predicted value as it varies with the values of the focal and its moderating variables

Author:
Robert L. Kaufman (Emeritus, Temple University)

Reference:
Robert L. Kaufman. 2018. Interaction Effects in Linear and Generalized Linear Models, Sage Publications.