```Date: Sun, 16 Nov 2008 16:10:44 -0800 Reply-To: dfisher@csulb.edu Sender: "SAS(r) Discussion" From: "Dennis G. Fisher, Ph.D." Organization: California State University, Long Beach Subject: Re: Urgent help with power related for binomial proportion Comments: To: Sophia Tong In-Reply-To: <200811162315.mAGBmJKU003090@malibu.cc.uga.edu> Content-Type: text/plain; charset="us-ascii" Sophia, Usually the value of P2 is a substantive decision. If you put in the values of P1 and P2, then the software will calculate delta for you. If you have SAS 9.2 then you can use Power and sample size application. If you have 9.1 then you might want to consider the analyst application in SAS that I find to be easier to use than the alternative of proc power which you can also use. Good luck. Dennis Dennis G. Fisher, Ph.D. Professor and Director Center for Behavioral Research and Services California State University, Long Beach 1090 Atlantic Avenue Long Beach, CA 90813 tel: 562-495-2330 x121 fax: 562-983-1421 -----Original Message----- From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of Sophia Tong Sent: Sunday, November 16, 2008 3:16 PM To: SAS-L@LISTSERV.UGA.EDU Subject: Urgent help with power related for binomial proportion Dear SAS -L listers, I am trying to calculate minimum detectable difference in a proposed study to cpmare with historical data. The sample size, proportion of historical data are known (n1 and P1 are know known). Power and Alpha are arbitarily decided as 0.8 and 0.025, sample size was also proposed for different numbers ( so, n2, beta and alpha are all known). I need find delta. I was trying to derive delta from sample size formular in a textbook and give it up after finding it's beyond my knowledge. Does anyone know how to do it in SAS, will PROC POWER do it? Or any formular people have already figured it out? My deadline is tomorow, you help is greatly appreciated. Thanks Sophia ```

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