The first stage in analyzing the data with exploratory
factor analysis is checking the conditions for a stable factor
structure (Ferguson and Cox 1993). This requires that the
sample size is large enough. The two most frequently used
criteria are the absolute minimum number of subjects and
the relative number indicated by the subjects-to-variables
ratio. Somewhere between 100 and 300 subjects have been
suggested as the minimum number of subjects, whereby
Guadagnoli and Velicer (1988) even suggested that 100
subjects may be acceptable. With 668 subjects in our
composite sample, this criterion is absolutely met. Recommendations
for the subject-to-variable ratio range
between 2:1 and 10:1. The generally accepted minimum
for reaching a stable factor structure is 5:1 (Ferguson and
Cox 1993). In our sample this ratio was 6.7:1, thus higher
than the generally accepted minimum ratio.