```Date: Mon, 14 Jul 2008 11:11:26 -0500 Reply-To: "Swank, Paul R" Sender: "SAS(r) Discussion" From: "Swank, Paul R" Subject: Re: PROC MEANS Comments: To: Nanita In-Reply-To: Content-Type: text/plain; charset="us-ascii" With an N of 19, a t distribution is more appropriate than Z unless you have the population standard deviation. Paul R. Swank, Ph.D. Professor and Director of Research Children's Learning Institute University of Texas Health Science Center - Houston -----Original Message----- From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of Nanita Sent: Monday, July 14, 2008 7:56 AM To: SAS-L@LISTSERV.UGA.EDU Subject: Re: PROC MEANS I have just one more question. LCLM= mean - 1.96*std_dev/(N)^0.5? UCLM =mean - 1.96*std_dev/(N)^0.5? If so, why do I have an output like this? N=19 Mean= 2.57046 StdDev= 0.11615 LCLM= 2.51447 UCLM = 2.62644 ? It shouldn't be: LCLM= 2.57046-(1.96*0.11615)/(19^0.5) = 2.518233 UCLM = 2.57046+(1.96*0.11615)/(19^0.5) = 2.622687 ???? On 14 Jul, 10:55, Nanita wrote: > Hi all, > > I have this code to calculate the confidence bands of set of data. > > proc means data =sort_ic > fw=12 > printalltypes > printidvars > alpha=0.05 > vardef=NF > chartype > mean > std > clm; > > var V_ASK V_BID V_MID; > > by codigo_param prazo; > id codigo_param prazo; > > output out=sort_ic_source > mean()= > std()= > lclm()= > uclm()= > / autoname autolabel inherit > ; > run; > > My question is... what is the destribuition used? Normal(0,1)?? > > Thanks in advance ```

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