I am trying to produce the coefficient of variation. I see that PROC MEANS calculates this simply as the STD/Arith.Mean, and I can verify that calculation if I output the std, mean, and cv.
However, I have also been told that PROC TTEST calculates the CV as well, when using the option dist=lognormal. In the past, I have only used this option for getting the geometric mean, so I was hesitant to use this to get the CV. However, the documentation does show that the CV is calculated. And while in the syntax documentation for TTEST itself, there is no mention of how CV is calculated, in this example, it states that the CV displayed with dist=lognormal is in fact the same: "The CV of 0.1676 is the ratio of the standard deviation to the (arithmetic) mean" (http://support.sas.com/documentation/cdl/en/statug/63033/HTML/default/viewer.htm#/documentation/cdl/en/statug/63033/HTML/default/statug_ttest_sect013.htm).
My problem is that these two PROCs do not give the same result. The simple test I did was a dataset of number 1-10. Obviously, the dist option is affecting the calculation of the CV somehow. Can anyone explain to me the difference? Thanks!
data junk;
input x;
datalines;
1
2
3
4
5
6
7
8
9
10
;
run;
ods listing;
proc ttest data = junk dist = lognormal;
var x;
run;
proc means data = junk n mean std cv;
var x;
run;
Message was edited by: Kastchei
(edited, since I had pasted in code that I had altered in an attempt to figure out the difference)
Message was edited by: Kastchei
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