Dear All,
A colleague has asked me for some help with the determination of the sample size required for the following study. The basic study will consist of sampling a number of matched pairs of areas (each area consisting of a number of herds – average of m in each say) in which an intervention is applied to one member of each pair that is expected to reduce the prevalence of a particular disease by 25% to what is expected in general. The unit of measurement is whether a herd is affected by disease or not. It is anticipated that all herds within an area will be sampled. So the question is given the fixed herd size per area of m say, how many pairs of areas should be sampled. Any help or guidance with regard to calculation or references would be much appreciated.
Best wishes,
Fred Newell.
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