A Step-by-Step Approach to Using SAS® for Univariate & Multivariate Statistics, Second Edition

Using the LSMEANS Statement to Analyze Data from Unbalanced Designs

So far, the examples presented in this chapter are what are known as balanced designs, meaning that the same number of observations or participants have been assigned to each group or cell. Of the 18 children in the aggression study (both examples), six were assigned to each of the three treatment conditions (i.e., 0 grams of sugar, 20 grams of sugar, and 40 grams of sugar). When a research design is balanced, it is generally appropriate to use the MEANS statement with PROC GLM.

In contrast, a research design is said to be unbalanced if the number of observations per cell are unequal. In the aggression study, for instance, if 8 children were assigned to the first treatment condition ...