PakMediNet Discussion Forum : Medical Research in Pakistan : sample size calculation
sample size calculation
i need to calculate the sample size for my study,need some articles regarding comparison of bleeding in septoplasty when two groups are compared ,one with nasal packing and other without nasal packing after surgery.
would anyone please help.
Thank you.
Posted by: ziarizvi Posts: 26 :: 19-01-2008 :: | Reply to this Message
Re: sample size calculation would someone please help?
Posted by: ziarizvi Posts: 26 :: 20-01-2008 :: | Reply to this Message
Re: sample size calculation What is the study design of your study? You need a biostatician help here. Before going to him collect information regarding the "prevelance of bleeding in septoplasty with nasal packing and without nasal packing" from the literature. There are formulas which can calculate the sample size. Why dont you ask CPSP Epidemiology people to help you.
Posted by: docosama Posts: 333 :: 20-01-2008 :: | Reply to this Message
Re: Re: sample size calculation
You need to provide more information how you would evaluate your outcome. Are you planning to define it as a dichotomous variable, that is proportion of patients who bled after septoplasty in nasal packing group versus no nasal packing group. In that case you will need to know the difference in proportions of bleeding in the two groups. If you don't know this proportion, you need to define what is the lowest clinically significant difference in proportions that you would like to detect. Once you have that, it should be easy to use any of the many online sample size calculators. My favourite is PS from Vanderbilt university available at this link:
http://biostat.mc.vanderbilt.edu/twiki/bin/view/Main/PowerSampleSize
Posted by: rqayyum Posts: 199 :: 21-01-2008 :: | Reply to this Message