Date:         Tue, 14 Nov 2006 13:29:29 -0800
Reply-To:     jn mao <jn_mao@YAHOO.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         jn mao <jn_mao@YAHOO.COM>
Subject:      question on Comparing two regression lines
In-Reply-To:  <000001c704c0$8c41e870$09005882@hpdv1267ea>
Content-Type: text/plain; charset=iso-8859-1

Hello SASLs,

  I have a continuous Y measured at 3 doses of drug A given (X) between two groups. My boss asked me to compare if overall Y is significant difference with 3 doses between 2 groups.  I did 'proc glm' to compare the regression line of Y with X (x=1, or 2 or 3 for 3 doses) between two groups. The interaction p value is >0.05. I did conclude that overall Y is not significantly different with increasing dose of drug A between two groups. Is that conclusion right?

  As my boss asked that the interaction is not significant only means that the two regression lines are parallel, but the difference between two parallel lines could be significant. He said there must be some else analysis that could answer the question of overall Y is different between two groups. Could someone help me on this question? Thanks much.

  Jane


---------------------------------
Cheap Talk? Check out Yahoo! Messenger's low PC-to-Phone call rates.