We are in the process of setting up audits for our specialty areas (anesthesiology, radiology & pathology) where coders do the CPT selection from documentation. Our billing system doesn't track the coders so we can't audit X encounters per coder (as we do with providers). We are thinking that our approach will be X% of total charges which would give us an adequate mix of coders but don't know the best way to determine a reasonable sample size. Does anyone perform this type of audit? If so, will you share your methodology for determination of sample size?