PakMediNet Discussion Forum : Biostatistics : sample size for case-control study
sample size for case-control study
How to calculate sample size in a case control study when we have noting before?
I have the formula specific for calculating the sample size in a case-control epidemiological study. this formula needs to know about the variance or the probability of the presence of risk factors in the population to use them in the formula. but, when we have no previous research in the field in that specific population, then we do not have the required information to use them in sample size formula. in this case how we can calculate the sample size? specifically, I want to study the risk factors of a rare disease in a retrospective case-control study.the population of those disease is about 1000 patient as the records. so, what could be the size for case and for control group?
Posted by: dokijoonPosts: 4 :: 26-03-2009 :: | Reply to this Message
Re: sample size for case-control studyIn this case, you can use 50% (0.5) as probability or variance in the formula.
Posted by: docosamaPosts: 333 :: 28-03-2009 :: | Reply to this Message