The FACTOR Procedure

PROC FACTOR provides a variety of factor extraction methods that you can specify by using the METHOD= option. Typically, the maximum number of factors that can be extracted is the same as the number of variables that are being factor-analyzed. Because factor analysis can be viewed as a data-reduction technique, the actual number of factors that researchers want to retain after the extraction is usually much smaller. PROC FACTOR provides the following three options that you can control the number of factors to retain in factor solutions: MINEIGEN=, NFACTORS=, and PROPORTION=. The NFACTORS= option specifies explicitly the number of factors to retain. Each of the other two options specifies a criterion value to determine the number of factors. See the MINEIGEN= and PROPORTION= options for details about how these criteria work.

If you specify two or more of these options, the number of factors retained is the minimum number satisfying any of the criteria. If you do not specify any of these options, PROC FACTOR essentially sets default criterion values for the MINEIGEN= and PROPORTION= options and retain the minimum number of factors that can satisfy either one of these criteria. See the MINEIGEN= and PROPORTION= options for details about the default criterion values, which depend on the extraction method that you use.