SPSS® 12.0 Command Syntax Reference

NOMREG 1071
the former effect must also be in the model. For example, if A, X, and A*X are specified,
then for A*X to be in a model, the effects A and X must also be in the model.
The containment requirement stipulates that, among the effects specified or implied on the
MODEL subcommand, for any effect to be in the model, all effects contained in the former
effect must also be in the model. For any two effects F and F’, F is contained in F’ if:
both effects F and F’ involve the same covariate effect, if any (Note that effects A*X and
A*X*X are not considered to involve the same covariate effect, because the first involves
covariate effect X and the second involves covariate effect X**2.),
F’ consists of more factors than F, and
all factors in F also appear in F’.
The following table illustrates how the hierarchy and containment requirements relate to the
RULE options. Each row of the table gives a different set of effects specified on the MODEL
subcommand. The columns correspond to the RULE options SINGLE, SFACTOR, and CON-
TAINMENT. The cells contain the order in which effects must occur in the model. For example,
unless otherwise noted, all effects numbered 1 must be in the model for any effects
numbered 2 to be in the model.
Table 1 Hierarchy and containment requirements
Effects SINGLE SFACTOR CONTAINMENT
1. A, B
A, B, A*B
2. A*B
X, X**2, X**3 1. X
2. X**2
3. X**3
A, X, X(A) 1. A, X
2. X(A)
A, X, X**2(A) 1. A, X
2. X**2(A)
OUTFILE Subcommand
1. A, B
2. A*B
Effects can occur in
the model in any
order.
Effects can occur in
the model in any
order.
Effects can occur in
the model in any
order.
1. A, B
2. A*B
Effects can occur in
the model in any
order.
1. X
2. X(A)
Effect A can occur in
the model in any
order.
Effects can occur in
the model in any
order.
The OUTFILE subcommand allows you to specify files to which output is written.