Interaction plot based on brkdn.plot function in plotrix package
iplotC(function1 = NULL, function2 = NULL, data, function3 = NULL, ...)
A function in the form ~depvar
A function. Here indepvar is typed before controlvar: ~indepvar + controlvar
Design dataset (e.g. nesD, gssD, statesD, or worldD)
A function. Here indepvar is typed after controlvar: ~controlvar + indepvar
Further arguments to be passed to brkdn plot
No value returned