st: xtile command for calculating tertiles

["Weichle, Thomas" <Thomas.Weichle@va.gov>]

Hi Statalisters,
Can anyone comment on the difference between the way Stata's -xtile-
command creates tertiles compared to the way the SAS -proc rank- creates
tertiles? And the differences in which ties are handled?  The following
are the code I'm using and I am getting slightly different results.  My
data do contain ties and I think this is the issue.

Stata:
xtile tertile = opcd, nquantiles(3)

SAS:
proc rank data = test out = ranks groups = 3;
	var opcd;
	ranks opcd_tert;
	run;

Tom Weichle
Math Statistician
Center for Management of Complex Chronic Care (CMC3)
Hines VA Hospital, Bldg 1, C202
708-202-8387 ext. 24261
Thomas.Weichle@va.gov 

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