02-07-2013 05:39 PM
Can someone help me update this code for SAS 9.2 or suggest better. I found it on the web in Google Groups from 1998.
Proc mixed doesn't compute lsd directly, but it can be done using info. generated by the make statement. Look at this example:
make "diffs" out=diffs;
05-16-2013 10:00 AM
You probably have different values for the standard error of the differences, as a result of unequal observations in the effects you are comparing. Consequently, the LSD will differ from case to case. Sharing some more code, especially your PROC MIXED code, and some info on the design could help clarify this.
05-17-2013 09:52 AM
Many thanks Steve.
below is the dode:
class block variety;
ods output Diffs=d;
This is an augmented design where 200 varieties and 5 checks have been tested in an Augmented randomized complete block design. The 200 varieties have been unreplicated in 20 blocks of 10 plots each. Each block has been completed by the 5 checks. Hence a total of 300 plots (200+5*20). Thanks
05-17-2013 10:44 AM
So in the lsmeans table, are the standard errors of the varieties all equal? If not, then there is probably some missing data (variety within a block), so that the standard error of the difference is not constant. Also, are the 5 checks all identical check varieties? This also leads to unequal replication, unequal standard errors of the differences, and consequently, different LSDs.
Also, in a design of this type, block by variety is often included, since not all varieties are seen in each block, but the check varieties are, and this may represent a better source of residual error. Emphasis on the word may, there.
11-30-2015 01:00 PM
In the equation
the value 0.05 represents the significance level, often denote by "alpha." So the answer to your question is that the LSD is for alpha=0.05. Use alpha=0.1 to get the LSD value that you are asking for.