Could someone please direct me to a reference or a URL that has information on decomposing and plotting a 3-way interaction in MRC? I have done this with a 2-way interactions before, but I'm not sure I've got it right when I extrapolate to a 3-way interaction. By "decompose", I mean to factor one of the effects out of the regression equation so that I can plug-in high (+1 sd), medium (0), and low (-1 sd) values for that effect. That way I can get estimates of Y for various combinations of high, med., and low values and plot them to get a visual depiction of the 3-way interaction. For example, if I have continuous variables A, B, and C. Based on some theory, I am predicting that there will be a 3-way interaction between them (A*B*C) that accounts for a substandial portion of the variance in a criterion (Y) beyond the variance accounted for by the main effects (A, B, C) and the 2-way interactions (A*B, A*C, B*C). If I think that the nature of the interaction is such that the 2-way interaction between A and B (A*B) will depend on values of C, how would I rearrange the regression equation (algebraically) so that I can hold C constant at some value of interest, and plug in values for the other effects to get an estimate of Y to plot? TIA, Brad =========================================================================== This list is open to everyone. Occasionally, less thoughtful people send inappropriate messages. Please DO NOT COMPLAIN TO THE POSTMASTER about these messages because the postmaster has no way of controlling them, and excessive complaints will result in termination of the list. For information about this list, including information about the problem of inappropriate messages and information about how to unsubscribe, please see the web page at http://jse.stat.ncsu.edu/ ===========================================================================
