test for significance


New Member
Hello everyone,

I'd like to analyse an intervention that was put into place at the hospital I work at to reduce central line infections. The first step I want to take is to establish whether or not the mean infection rates in the pre and post-intervention periods are significantly different. I have monthly infection rates (infections/1000 device days) for about 3 years before the intervention and for about 18 months after the intervention.

Could someone please advise me as to what the best test to use would be?

Thank you very much.