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SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

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198 <strong>Syntax</strong> <strong>Reference</strong><br />

DIMENSION Subcommand<br />

DIMENSION specifies the number of dimensions (components) you want CATPCA to<br />

compute.<br />

• The default number of dimensions is 2.<br />

• DIMENSION is followed by an integer indicating the number of dimensions.<br />

• If there are no variables specified as MNOM (multiple nominal), the maximum number of<br />

dimensions you can specify is the smaller of the number of observations minus 1 and the<br />

total number of variables.<br />

• If some or all of the variables are specified as MNOM (multiple nominal), the maximum<br />

number of dimensions is the smaller of a) the number of observations minus 1 or b) the<br />

total number of valid MNOM variable levels (categories) plus the number of SPORD,<br />

SPNOM, ORDI, NOMI, and NUME variables minus the number of MNOM variables without<br />

missing values.<br />

• CATPCA adjusts the number of dimensions to the maximum if the specified value is too<br />

large.<br />

• The minimum number of dimensions is 1.<br />

NORMALIZATION Subcommand<br />

The NORMALIZATION subcommand specifies one of five options for normalizing the object<br />

scores and the variables. Only one normalization method can be used in a given analysis.<br />

VPRINCIPAL This option optimizes the association between variables. With<br />

VPRINCIPAL, the coordinates of the variables in the object space are<br />

the component loadings (correlations with principal components such<br />

as dimensions and object scores). This is the default if the<br />

NORMALIZATION subcommand is not specified. This is useful when<br />

you are primarily interested in the correlations between the variables.<br />

OPRINCIPAL This option optimizes distances between objects. This is useful when<br />

you are primarily interested in differences or similarities between the<br />

objects.<br />

SYMMETRICAL Use this normalization option if you are primarily interested in the<br />

relation between objects and variables.<br />

INDEPENDENT Use this normalization option if you want to examine distances<br />

between objects and correlations between variables separately.<br />

The fifth method allows the user to specify any real value in the closed interval [ – 1 , 1]. A<br />

value of 1 is equal to the OPRINCIPAL method, a value of 0 is equal to the SYMMETRICAL<br />

method, and a value of – 1 is equal to the VPRINCIPAL method. By specifying a value greater<br />

than –<br />

1 and less than 1, the user can spread the eigenvalue over both objects and variables.<br />

This method is useful for making a tailor-made biplot or triplot. If the user specifies a value<br />

outside of this interval, the procedure issues a syntax error message and terminates.

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