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SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

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880 MANOVA: Multivariate<br />

WILKS Wilks’ lambda. The intervals are computed by approximating the percentage<br />

points with percentage points of the F distribution.<br />

HOTELLING Hotelling’s trace. The intervals are computed by approximating the percentage<br />

points with percentage points of the F distribution.<br />

BONFER Bonferroni intervals. This approximation is based on Student’s t distribution.<br />

• The Wilks’, Pillai’s, and Hotelling’s approximate confidence intervals are thought to<br />

match exact intervals across a wide range of alpha levels, especially for large sample sizes<br />

(Burns, 1984). Use of these intervals, however, has not been widely investigated.<br />

• To obtain multivariate intervals separately for each parameter, choose individual multivariate<br />

intervals. For individual multivariate confidence intervals, the hypothesis degree<br />

of freedom is set to 1, in which case Hotelling’s, Pillai’s, Wilks’, and Roy’s intervals will<br />

be identical and equivalent to those computed from percentage points of Hotelling’s<br />

distribution. Individual Bonferroni intervals will differ and, for a small number of dependent<br />

variables, will generally be shorter.<br />

• If you specify MULTIVARIATE on CINTERVAL, you must specify a type keyword. If you<br />

specify CINTERVAL without any keyword, the default is the same as with univariate analysis—CINTERVAL<br />

displays individual-univariate confidence intervals at the 0.95 level.<br />

ANALYSIS Subcommand<br />

ANALYSIS is discussed in MANOVA: Univariate as a means of obtaining factor-by-covariate<br />

interaction terms. In multivariate analyses, it is considerably more useful.<br />

• ANALYSIS specifies a subset of the continuous variables (dependent variables and<br />

covariates) listed on the MANOVA variable list and completely redefines which variables<br />

are dependent and which are covariates.<br />

• All variables named on an ANALYSIS subcommand must have been named on the<br />

MANOVA variable list. It does not matter whether they were named as dependent variables<br />

or as covariates.<br />

• Factors cannot be named on an ANALYSIS subcommand.<br />

• After the keyword ANALYSIS, specify the names of one or more dependent variables and,<br />

optionally, the keyword WITH followed by one or more covariates.<br />

• An ANALYSIS specification remains in effect for all designs until you enter another<br />

ANALYSIS subcommand.<br />

• Continuous variables named on the MANOVA variable list but omitted from the ANALYSIS<br />

subcommand currently in effect can be specified on the DESIGN subcommand. See the<br />

DESIGN subcommand on p. 863 in MANOVA: Univariate.<br />

• You can use an ANALYSIS subcommand to request analyses of several groups of variables<br />

provided that the groups do not overlap. Separate the groups of variables with slashes and<br />

enclose the entire ANALYSIS specification in parentheses.<br />

T 2

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