Factor analysis
As mentioned earlier, the WHOQOL-100 was
based on six theoretical domains that were subsequently
reorganised into four domains during the
development of the WHOQOL-BREF. Empirical
evidence showed that facets from the independence
and spirituality domains were associated with the
physical and psychological domains respectively,
and that a 4-factor solution fits the data better in
both ill and well populations. Exploratory factor
analyses (Varimax rotation) provided no evidence
of a better model. Analysis of the total population
data showed four factors (eigenvalues >1.0) that
explained 53% of the variance in the data. Centrespecific
analyses showed that most sites had four to
six eigenvalues greater than 1.0 (mode ¼ 5; range
3–7) and these explained 50–81% of the variance.