Date: Wed, 9 Apr 2003 19:13:40 +0000 Sender: "SAS(r) Discussion"
<SAS-L@LISTSERV.UGA.EDU> Subject: Re: sampling and control
groups (fwd) The formula you are referring to is to do point
estimates of a proportion. With that formula you calculate the
sample size to estimate the proportion of something in a
population. To do a sample size calculation to compare a
treatment group against a control group you should define what
you are comparing means, proportion or something else. If you
are testing a hypothesis between the test and control group, you
need to do a sample calculation that takes in consideration th
significance and power level of your test. If you are interested
in estimating the difference between the two groups then doing a
sample size estimation at a particular significance and margin
of error should be fine. Refer to Sample size Methodology by M.
M. Desu and D. Raghavarao, published by Academic press. For the
point estimates refer to Sampling Thechniques by Cochran,
published by Wiley. Hope this