topic need Help with contrast statement in SAS Procedures

need Help with contrast statement

EhsanKhedive — Fri, 14 Mar 2014 09:54:54 GMT

I have a 3*6 (3 nitrogen rates and 6 rice varieties) factorial design and I don't know how to make any contrast I need. Ive looked up SAS/STAT help but didn't find the answer. The questions are as follow:

comparison between Linear interaction of nitrogen with variety 6 vs. other varieties. ie. NL*(V6 vs. others). (NL means the linear interaction with Nitrogen factor).

NL*

NL*(V2 vs. V5)

NL*(V1 vs. V3 vs. V4)

Quadratic interactions are same as linear:

NQ*(V6 vs. others)

NQ*

NQ*(V2 vs. V5)

NQ*(V1 vs. V3 vs. V4)

The data are attached.

Thank you in advance

Re: need Help with contrast statement

SteveDenham — Fri, 14 Mar 2014 12:51:26 GMT

Some comments:

PROC GLM does not correctly calculate standard errors for split plot and strip plot designs. Let me repeat that. PROC GLM does not correctly calculate standard errors for split plot and strip plot designs.

Get a copy of SAS for Mixed Models, 2nd ed. by Littell et al., to see code for PROC MIXED for this design, and many examples of contrasts.

If you fit your data with a mixed model, consider using LSMESTIMATE statements (either in PROC GLIMMIX or PROC PLM), and it becomes straightforward to compare lsmeans of interest.

Steve Denham

Re: need Help with contrast statement

EhsanKhedive — Fri, 14 Mar 2014 13:25:27 GMT

Thank you very much, I found my way out with this book.

Best Regards