https://communities.sas.com/t5/Statistical-Procedures/PROC-POWER-Find-sample-size-for-specified-precision-of/m-p/767108#M37495 <P>Specify a wide range of sample sizes (ntotal=) and then whittle it down to find the desired sample size.</P> <PRE><CODE class=" language-sas">proc power; onesamplefreq ci halfwidth = 0.018 proportion = 0.025 ntotal = 110 to 120 probwidth = .; run;</CODE></PRE> Fri, 10 Sep 2021 19:35:36 GMT StatDave 2021-09-10T19:35:36Z https://communities.sas.com/t5/Statistical-Procedures/PROC-POWER-Find-sample-size-for-specified-precision-of/m-p/767100#M37494 <P>I'd like to use Proc Power to estimate a required sample size as follows:<BR />Outcome is binary (Bernoulli trial).<BR />Expected population success rate is 0.025.<BR />What sample size will produce a 95% confidence interval for success rate with a width of 0.036 (half width = 0.018)?</P><P>&nbsp;</P><P><STRONG>Question</STRONG>: Can this be done with Proc Power and if so how?&nbsp;The CI method (exact, Wald, etc.) isn't important at this point.</P><P>Thanks for help!</P><P>--<BR />John Uebersax</P> Fri, 10 Sep 2021 19:04:22 GMT https://communities.sas.com/t5/Statistical-Procedures/PROC-POWER-Find-sample-size-for-specified-precision-of/m-p/767100#M37494 jsuebersax 2021-09-10T19:04:22Z https://communities.sas.com/t5/Statistical-Procedures/PROC-POWER-Find-sample-size-for-specified-precision-of/m-p/767108#M37495 <P>Specify a wide range of sample sizes (ntotal=) and then whittle it down to find the desired sample size.</P> <PRE><CODE class=" language-sas">proc power; onesamplefreq ci halfwidth = 0.018 proportion = 0.025 ntotal = 110 to 120 probwidth = .; run;</CODE></PRE> Fri, 10 Sep 2021 19:35:36 GMT https://communities.sas.com/t5/Statistical-Procedures/PROC-POWER-Find-sample-size-for-specified-precision-of/m-p/767108#M37495 StatDave 2021-09-10T19:35:36Z