Factor Analysis in Stata

1. factor [varlist], Choose variables to analyze.

pc | pcf | pf | ipf | ml Choose type of analysis:

pc - principal components

pcf - principal component factors

pf - principal factors (default)

ipf - iterated principal factors

ml - maximum likelihood

key modifiers:

factors (#) Select maximum # of common factors.

mineigen (#) Set eigenvalue minimum for common factor.

covariance Analyze covariance matrix (in pc only).

2. greigen Graph eigenvalues for "scree plot".

3. rotate varimax Choose orthogonal rotation.

promax (#) Choose nonorthogonal (oblique)

rotation. (# defines correlation)

4. predict bartlett Use (unbiased) Bartlett method rather than

default regression method (smaller MSE).

norotate Score unrotated factors.

Sample analysis:

factor x1 x2 x3 x4 x5 x6 x7 x8 x9, ipf

geigen

factor x1 x2 x3 x4 x5 x6 x7 x8 x9, ipf factor (3)

rotate varimax

predict bartlett

The first command factor analyzes 9 variables (x1 through x9) using iterated principal factor analysis. Command 2 graphs the eigenvalues by factor number. Based on the results of the first two command, a decision is made to retain three common factors with command 3. The fourth command provides an orthogonally rotated (varimax) solution. The last command produces factor scores for each of the three factors using Bartlett's algorithm.