Date: Mon, 11 Sep 2006 12:41:57 +0530
Reply-To: Madan Gopal Kundu <Madan.Kundu@RANBAXY.COM>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: Madan Gopal Kundu <Madan.Kundu@RANBAXY.COM>
Subject: Re: McNemar test in SAS
Content-Type: text/plain; charset="US-ASCII"
Dear David,
Thanks a lot for your quick response. As usual it is a great reply and
is of great help to me.
Best Regards,
MADAN
-----Original Message-----
From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of
David L Cassell
Sent: 11 September 2006 12:34
To: SAS-L@LISTSERV.UGA.EDU
Subject: Re: McNemar test in SAS
Madan.Kundu@RANBAXY.COM wrote:
>
>Hi,
>
>=0D
>
>I want to compute McNemar test with the following data:
>
>=0D
>
>data abc;
>
>input x $ y $ count;
>
>cards;
>
>Absent Absent 256
>
>Absent Present 0
>
>Present Absent 88
>
>Present Present 0
>
>;
>
>run;
>
>=0D
>
>proc freq data=3Dabc;
>
>table x*y/agree;
>
>weight count;
>
>run;
>
>=0D
>
>But log shows that:
>
>NOTE: No statistics are computed for x * y since y has less than 2
>nonmissing levels.
>
>=0D
>
>However, with the formula given in book it can be computed manually. So
>I am wonder why SAS does not produce the McNemar test statistic. Is
this
>a software limitation???? ..... or anything else...
>
>=0D
>
>Kind Regards,
>
>MADAN
SAS is seeing a 1x2 vector without enough data to do the
computations. Look at the output that oyu have, and you'll
see that. If you have SAS 9, you can try the ZEROS option
with the AGREE option and see how SAS likes that.
Or you can change the 0 values to something near zero, say
1E-8, and run the proc. It will compute the results, but of
course you'll get an insanely small p-value because of your
data. I can compute that without trying.
HTH,
David
--
David L. Cassell
mathematical statistician
Design Pathways
3115 NW Norwood Pl.
Corvallis OR 97330
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