Comparing frequency between groups I'm using SPSS, new to statistics.
I have 2 groups of patients (Group 1: 1000 patients; Group 2: 400 patients).
One of five different interventions (surgery a,b,c,d,e) was performed on subjects in each Group.
I want to compare the frequency of each intervention between the  groups (obtaining a P value).
So I want to say:
there was/was not a statistically significant difference (P-value) in the number of 'interventions a" between the two groups.
Thanks

Use a 2-way chi-squared test, with group vs intervention as the two variables.
