Which statistcal test do I use on SPSS to evaluate gender differences in 2 conditions?

Question

Question: Test the impact of the intervention and gender on tanning trips made at 6 months. (i have the data set)

Answer 1

You could either use Analysis of Variance (ANOVA) or a series of 2-sample t-tests (one for each pair of things you are comparing).

Answer 2

Do you mean 6 month intervals? If so ANOVA would be ok but t-test would only be appropriate for the intervention data as data would be either interval or ratio.. However for the gender condition it would be more appropriate to use sign test or possibly even chi squareas data would be nominal .