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Can someone point me to where I can see how differences of LSMEANS are calculated in GLIMMIX using the DIFF option?
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TDIFF is the t-value of the test to see if the LSMEANS are different. PDIFF is the probability associated with the t-value.
Paige Miller
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LSMEANS calculations: https://documentation.sas.com/?docsetId=statug&docsetTarget=statug_glm_details41.htm&docsetVersion=1...
Essentially, Least Squares Means tries to adjust for different number of observations in cells, which can bias the calculation of regular old means.
Paige Miller
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Thanks for replying! I am actually interested in the calculations that are used in the DIFF option, which compares one LSMEAN to another, because I am trying to understand how it compares to a Fisher's LSD test.
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First you calculate the individual LSMEANS and then you do a subtraction to get a DIFF.
The formula for Fisher's LSD is here: https://www.statisticshowto.com/how-to-calculate-the-least-significant-difference-lsd/
So I believe that FIsher's LSD uses the difference of actual factor means while LSMEANS uses the difference of least-squares means. So the difference between two means won't even agree.
Paige Miller
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I don't understand what you are saying.
Paige Miller
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Here's a worked example: https://support.sas.com/kb/24/984.html
Paige Miller
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TDIFF is the t-value of the test to see if the LSMEANS are different. PDIFF is the probability associated with the t-value.
Paige Miller
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