PakMediNet Discussion Forum : Biostatistics : sample size in case and control study
sample size in case and control studysample size in case and control study shud b equal or it can b any no.like suppose if control is 200 case no shud also b same or it can vary.
Posted by: nabeelaPosts: 2 :: 19-07-2009 :: | Reply to this Message
Re: sample size in case and control studyi have sent u mail, in which i tried to explain the answer of your problem
Posted by: ibrahim_apPosts: 138 :: 02-08-2009 :: | Reply to this Message
Re: sample size in case and control studyGenerally stated, for a case-control study, number of individuals can vary in cases and controls. Usually controls are easier to come by, so the reason for unequal sample size is to have sufficient power. You can have a 1:2 or 1:3 ratio between cases and controls (or anything in-between). However, once you are beyond 1:4 ratio, there is really not much benefit of increasing sample size. However, in your case, I am not sure what is the need. There are slight issues with statistical analysis when calculating variances but I will not be worried about it. Most statistical programs, if told, can adjust for this.
Posted by: rqayyumPosts: 199 :: 24-12-2009 :: | Reply to this Message
Re: Re: sample size in case and control studysir, is there any formula to calculate sample size
Posted by: BVHOSPITALPosts: 131 :: 27-12-2009 :: | Reply to this Message
Re: sample size in case and control studyThere are very many formula for sample size calculation, which one will be used depends on study question. There may be some studies for which there is no formula and in that case simulation can be used to calculate sample size. This is why research question is so important in calculating sample size.
Posted by: rqayyumPosts: 199 :: 27-12-2009 :: | Reply to this Message