The PHREG Procedure

LSMEANS Statement

LSMEANS <model-effects> </ options> ;

The LSMEANS statement compares least squares means (LS-means) of fixed effects. LS-means are predicted population margins—that is, they estimate the marginal means over a balanced population. In a sense, LS-means are to unbalanced designs as class and subclass arithmetic means are to balanced designs.

Table 67.8 summarizes the options available in the LSMEANS statement. If the BAYES statement is specified, the ADJUST=, STEPDOWN, and LINES options are ignored. The PLOTS= option is not available for the maximum likelihood analysis. It is available only for the Bayesian analysis.

Table 67.8: LSMEANS Statement Options

Option	Description
Construction and Computation of LS-Means
AT	Modifies the covariate value in computing LS-means
BYLEVEL	Computes separate margins
DIFF	Requests differences of LS-means
OM=	Specifies the weighting scheme for LS-means computation as determined by the input data set
SINGULAR=	Tunes estimability checking
Degrees of Freedom and p-values
ADJUST=	Determines the method for multiple-comparison adjustment of LS-means differences
ALPHA= $\alpha$	Determines the confidence level ( $1-\alpha$ )
STEPDOWN	Adjusts multiple-comparison p-values further in a step-down fashion
Statistical Output
CL	Constructs confidence limits for means and mean differences
CORR	Displays the correlation matrix of LS-means
COV	Displays the covariance matrix of LS-means
E	Prints the $\mb {L}$ matrix
LINES	Produces a “Lines” display for pairwise LS-means differences
MEANS	Prints the LS-means
PLOTS=	Requests graphs of means and mean comparisons
SEED=	Specifies the seed for computations that depend on random numbers

For details about the syntax of the LSMEANS statement, see the section LSMEANS Statement of Chapter 19: Shared Concepts and Topics.