https://communities.sas.com/t5/Statistical-Procedures/PROC-MIXED-The-covariance-of-difference-between-two-groups/m-p/795103#M39006 <P>May you please help me understand how I could get cov(1,2)&nbsp; for difference between 2 groups in proc mixed? I looked at the book "SAS for Mixed Models, 2nd Edition, by R. Littell et al. (SAS Press)" but still I do not find the answer.</P><P>In diffs output, only estimate and stderr included, but not covariance.</P><P>&nbsp;</P><P>Thanks</P> Wed, 09 Feb 2022 03:45:31 GMT pengznuc 2022-02-09T03:45:31Z https://communities.sas.com/t5/Statistical-Procedures/PROC-MIXED-The-covariance-of-difference-between-two-groups/m-p/795103#M39006 <P>May you please help me understand how I could get cov(1,2)&nbsp; for difference between 2 groups in proc mixed? I looked at the book "SAS for Mixed Models, 2nd Edition, by R. Littell et al. (SAS Press)" but still I do not find the answer.</P><P>In diffs output, only estimate and stderr included, but not covariance.</P><P>&nbsp;</P><P>Thanks</P> Wed, 09 Feb 2022 03:45:31 GMT https://communities.sas.com/t5/Statistical-Procedures/PROC-MIXED-The-covariance-of-difference-between-two-groups/m-p/795103#M39006 pengznuc 2022-02-09T03:45:31Z https://communities.sas.com/t5/Statistical-Procedures/PROC-MIXED-The-covariance-of-difference-between-two-groups/m-p/795166#M39008 <P>I think using the COVB option in the MODEL will give you what you want.</P> <P>&nbsp;</P> <P>SteveDenham</P> Wed, 09 Feb 2022 13:41:01 GMT https://communities.sas.com/t5/Statistical-Procedures/PROC-MIXED-The-covariance-of-difference-between-two-groups/m-p/795166#M39008 SteveDenham 2022-02-09T13:41:01Z