why do we use the term contrast in an equation? what is the dummy variable that will be used as a comparison in the test of significant interaction? what does a contrast test what is the difference between main effect and contrast what is a comparison in regression which of the following variables has a nonlinear interaction how to test significance of interaction in lr how to test significance of the interaction? what is the value of a contrast which of the following is a standard method of testing for the statistical significance of an interaction? how to test the significance of the interactions on the pt graph? which of the following is a way to test the importance of a linear interaction? what's the difference between a normal and a nonlinear model? how to test the difference from the null hypothesis what is the standard deviation of a regression test? how to test correlation for a regression how do you write the test of significant interaction which of the following is an example of a contrast matrix? how to test the significance of interaction when to use contrast