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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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LMATRIX Subcommand<br />

UNIANOVA 1611<br />

The LMATRIX subcommand allows you to customize your hypotheses tests by specifying the<br />

L matrix (contrast coefficients matrix) in the general form of the linear hypothesis LB = K,<br />

where K = 0 if it is not specified on the KMATRIX subcommand. The vector B is the parameter<br />

vector in the linear model.<br />

• The basic format for the LMATRIX subcommand is an optional label in quotation marks,<br />

an effect name or the keyword ALL, and a list of real numbers. There can be multiple effect<br />

names (or the keyword ALL) and number lists.<br />

• The optional label is a string with a maximum length of 255 characters. Only one label<br />

can be specified.<br />

• Only valid effects appearing or implied on the DESIGN subcommand can be specified on<br />

the LMATRIX subcommand.<br />

• The length of the list of real numbers must be equal to the number of parameters<br />

(including the redundant ones) corresponding to that effect. For example, if the effect A*B<br />

takes up six columns in the design matrix, then the list after A*B must contain exactly six<br />

numbers.<br />

• A number can be specified as a fraction with a positive denominator—for example, 1/3<br />

or –1/3, but 1/–3 is invalid.<br />

• A semicolon (;) indicates the end of a row in the L matrix.<br />

• When ALL is specified, the length of the list that follows ALL is equal to the total number<br />

of parameters (including the redundant ones) in the model.<br />

• Effects appearing or implied on the DESIGN subcommand but not specified here are<br />

assumed to have entries of 0 in the corresponding columns of the L matrix.<br />

• Multiple LMATRIX subcommands are allowed. Each is treated independently.<br />

Example<br />

UNIANOVA DEP BY A B<br />

/LMATRIX = “B1 vs B2 at A1”<br />

B 1 -1 0 A*B 1 -1 0 0 0 0 0 0 0<br />

/LMATRIX = “Effect A”<br />

A 1 0 -1<br />

A*B 1/3 1/3 1/3<br />

0 0 0<br />

-1/3 -1/3 -1/3;<br />

A 0 1 -1<br />

A*B 0 0 0<br />

1/3 1/3 1/3<br />

-1/3 -1/3 -1/3<br />

/LMATRIX = “B1 vs B2 at A2”<br />

ALL 0<br />

0 0 0<br />

1 -1 0<br />

0 0 0 1 -1 0 0 0 0<br />

/DESIGN = A, B, A*B.<br />

Assume that factors A and B each have three levels. There are three LMATRIX subcommands;<br />

each is treated independently.

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