I am conducting an ANCOVA with three covariates, Tank as random effect nested with Diet which includes a repeated measures analysis in Proc Mixed. I would like to create graphs showing the effect of the treatment (i.e. Diet) on various response variables (e.g. growth, stocking density and pigmentation), but without error bars. Instead, I would like to use a value summarising the treatment error, such as the standard error of the mean (SEM). However, I am unsure whether this parameter is valid for this type of ANCOVA and which table to take the values from. Both the “Solution for fixed effects” and the “Least squares means” have the value estimate and the standard error for each diet.
Could someone please guide me? I have found several different versions of the error summary, such as Root Mean Square Error, Pooled SEM from treatment LSMEANs, or standard error from an overall treatment contrast.
