Hello,
I have run into a strange problem. I am running N-way anova and what I have found out is if i change the order of the variables that I am using in the anova, then the P-values are changing
E.g. when I run the below procedure
ods noproctitle;
ods graphics / imagemap=on;
proc glm data=WORK.INTERNETDATA;
class Exits Continent Sourcegroup Uniquepageviews Bounces Visits;
model Timeinpage=Exits Continent Sourcegroup Uniquepageviews Bounces Visits /
ss1 ss3;
lsmeans Exits Continent Sourcegroup Uniquepageviews Bounces Visits /
adjust=tukey pdiff=all alpha=0.05 cl;
quit;
The value of Sourcegroup is significant i.e. 0.0037
Now when i change the sequence of the variable Bounces to something like this
ods noproctitle;
ods graphics / imagemap=on;
proc glm data=WORK.INTERNETDATA;
class Bounces Exits Continent Sourcegroup Uniquepageviews Visits;
model Timeinpage=Bounces Exits Continent Sourcegroup Uniquepageviews Visits /
ss1 ss3;
lsmeans Bounces Exits Continent Sourcegroup Uniquepageviews Visits /
adjust=tukey pdiff=all alpha=0.05 cl;
quit;
The value of the variable Souregroup is no longer significant i.e. 0.0752
Can somebody tell me why is this occuring.
Thanks and regards,
Aditya
It is difference between SS3 and SS1. If you only use SS3 , you will get the same P-value , otherwise if you use SS1 ,you will get different one. proc glm data=sashelp.class; class age sex; model weight=age sex/solution ss3; run; proc glm data=sashelp.class; class age sex; model weight=sex age/solution ss3; run;
It is difference between SS3 and SS1. If you only use SS3 , you will get the same P-value , otherwise if you use SS1 ,you will get different one. proc glm data=sashelp.class; class age sex; model weight=age sex/solution ss3; run; proc glm data=sashelp.class; class age sex; model weight=sex age/solution ss3; run;
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