Date:         Tue, 21 Dec 2010 09:58:19 -0500
Reply-To:     bbser 2009 <bbser2009@GMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         bbser 2009 <bbser2009@GMAIL.COM>
Subject:      what's wrong with proc means?
Content-Type: text/plain; charset="US-ASCII"

Greetings!

Running the code below, I ended up with the output data set like this:

chol         _TYPE_    _FREQ_   ...
Missing        0         11
Low            1         6
High           1         5

Notice the "grand mean" line starts with "Missing". Why?

If you change the class statement in the proc means below to this one:

class chol/missing;

Then there are two lines led by "Missing" like below. Why again?

chol         _TYPE_    _FREQ_   ...
Missing        0         15
Missing        1         4
Low            1         6
High           1         5

Thank you very much.

Max

---------- code -------------------

data blood;
    input subject rbc wbc chol;
cards;
1 7.4 7710 258
2 4.7 6560 .
3 7.53 5690 184
4 6.85 6680 .
5 7.72 . 187
6 3.69 6140 142
7 4.78 6550 290
8 4.96 5200 151
9 5.66 . 311
10 5.55 7710 .
11 5.62 . 152
12 5.85 7410 241
13 4.37 5780 .
14 6.94 5590 152
15 6.03 6520 217
;
*proc print data=blood;
*run;

proc format;
   value chol_group
     low -< 200 = 'Low'
     200 - high = 'High'
     .="Missing";
run;

title "proc means, output data set, class Chol/missing;";
proc means data=blood mean maxdec=1 noprint;
   class Chol;
   format Chol chol_group.;
   var RBC WBC;
   output out=temp
        mean= / autoname;
run;

proc print data=temp noobs;
run;