Date:         Tue, 28 Jul 2009 09:07:53 -0700
Reply-To:     elodie <elodie.gillain@GMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         elodie <elodie.gillain@GMAIL.COM>
Organization: http://groups.google.com
Subject:      sample size question when using proc mixed
Comments: To: sas-l@uga.edu
Content-Type: text/plain; charset=ISO-8859-1

Hi everyone,

I am running a (longitudinal) proc mixed analysis. The table below
gives the sample size at each timepoint from time=0 through time=4.

time    Samplesize
0          81
1          43
2          33
3          24
4          24

The output of proc mixed says there are 51 subjects in the analysis,
with a max of 5 observations per subject. The output also says Number
of Observations Read is 205, and the Number of Observations Used is
167.

I am not sure how there can be 51 subjects used for this analysis. I
am guessing that it is OK for a subject to have data at time 0, but
not at time 3 for example. Am I right?

I greatly appreciate your help.