I need some help about repeated measurement ANOVA.
We are investigating the effect of some intervention on reducing blood stream infection (BSI) rate in some wards. We plan to capture the BSI rate information at a monthly basis, 12 months without intervention first, then 12 months with intervention.
We are thinking of doing either time-series or repeated measurement ANOVA, I prefer the later one before I don't have much idea to do on the first one (extra question: too little time points, right?), but then here come another problem, how many wards do we need to show that there is really a statistically significant effect of intervention on BSI rate?
I think I'll do two ANOVA, one for "before intervention", one for "during intervention", and I suppose that the ANOVA "before intervention" should not have a significant F-ratio test.
I consider the term "sample size" two-dimensionally, either the number of wards, or the number of repeated measurements.