I'm very new to SPSS (using version 21) and statistics in general and am a bit stuck!
I need to do a multiple regression (I'm looking at how attitudes predict behaviour). I have one DV with continuous data and two IVs, also both with continuous data, but one IV has two nominal levels (these are two age groups, so I want to compare attitudes and behaviour for each age group).
I don't know whether I need to run two separate regressions for each level or combine them in one. Combining them makes more sense but I have no idea how to do this. If I ran two separate regressions then would I have to recheck parametric assumptions for each set of data?
I've been trying to figure this out for two days and am just not getting anywhere. Any help will be greatly appreciated.