```Date: Thu, 15 Oct 2009 09:58:50 +0200 Reply-To: Anders Mørup Jensen Sender: "SAS(r) Discussion" From: Anders Mørup Jensen Organization: TDC Totalloesninger Subject: Re: how to simulate clinical trial data which has lognormal Comments: To: sas-l@uga.edu As I understand the OP, he wanted the lognormal sample to have Mean=2 and Std=1 (not the underlying normal distribution). With a litle algebra applied to wellknown formulas for the mean and variance of a lognormal distribution (see e.g. Wikipedia) this means that the underlying normal distribution should have: Mean value = 2*log(2) - log(5)/2 Variance = log(5/4); resulting in the need1 dataset below. data need; /* ynorm has mean 2 and standard deviation 1 */ do i=1 to 200; ynorm=rannor(0)+2; ylognorm=exp(ynorm); output; end; run; proc means data=need; var ylognorm; run; data need1; /* ylognorm has mean 2 and standard deviation 1 */ do i=1 to 20000; ynorm=sqrt(log(5/4))*rannor(0)+(2*log(2)-log(5)/2); ylognorm=exp(ynorm); output; end; run; proc means data=need1; var ylognorm; run; / Anders "Ya Huang" skrev i en meddelelse news:200910142008.n9EF4ebt011509@malibu.cc.uga.edu... > /* If X is a random variable with a normal distribution, > then Y = exp(X) has a log-normal distribution; > likewise, if Y is log-normally distributed, > then log(Y) is normally distributed. */ > > data need; > do i=1 to 200; > ynorm=rannor(0)+2; > ylognorm=exp(ynorm); > output; > end; > run; > > ods listing close; > ods pdf file="c:\temp\junk.pdf"; > > goptions reset=all device=sasprtc; > > proc gchart data=need; > vbar ylognorm; > vbar ynorm; > run; > > ods _all_ close; > > > On Wed, 14 Oct 2009 11:09:48 -0700, jingtailan@gmail.com > wrote: > >>all: >> >>please advise on >>1. how to use SAS8.2 to create a data set which has >>N=200 >>mean=2 >>std=1 >>distribution=lognormal >> >>2 After creation of these data, what procedure I should use to get PDF >>graph? >> >>thanks a lot. >>jingtailan ```

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