I want to create an interaction term in SPSS on two continuous variables (ticket price and household income) in order to use this interaction term in a multiple regression model and test whether my main effects or interaction effects model is better.
Compute a new variable for each IV (the score minus the mean) and then an interaction term between these new variables?
Or compute an interaction term between the original IVs? (I have 105 observations)
Or do I re-code each of the IVs into categories e.g. low, med, high income/ticket price and then compute an interaction term that multiplied the two new categorical variables?
I had just created a new categorical variable for income (low,mid, high) and left the ticket price as is, but now I'm doing option 1 as I read this online.