Linear Mixed Models EM Means
Estimated Marginal Means of Fitted Models. This group allows you to request modelpredicted estimated marginal means of the dependent variable in the cells and their standard errors for the specified factors. Moreover, you can request that factor levels of main effects be compared.

Factor(s) and Factor
Interactions. This list contains factors and factor
interactions that have been specified in the Fixed dialog box, plus
an
OVERALL
term. Model terms built from covariates are excluded from this list. 
Display Means for. The procedure will compute the estimated marginal means for factors
and factor interactions selected to this list. If
OVERALL
is selected, the estimated marginal means of the dependent variable are displayed, collapsing over all factors. Note that any selected factors or factor interactions remain selected unless an associated variable has been removed from the Factors list in the main dialog box.  Compare Main Effects. This option allows you to request pairwise comparisons of levels of selected main effects. The Confidence Interval Adjustment allows you to apply an adjustment to the confidence intervals and significance values to account for multiple comparisons. The available methods are LSD (no adjustment), Bonferroni, and Sidak. Finally, for each factor, you can select a reference category to which comparisons are made. If no reference category is selected, all pairwise comparisons will be constructed. The options for the reference category are first, last, or custom (in which case, you enter the value of the reference category).
Obtaining Estimated Marginal Means for Linear Mixed Models
This feature requires Custom Tables and Advanced Statistics.
 From the menus choose:
 Optionally, select subjects and repeated variables, and then click Continue.
 In the Linear Mixed Models dialog box, click EM Means.
 Specify the estimated marginal means that you want.