Examining the relationship between global and domain measures of quality of life by three factor structure models

This study examined the relationship between global and domain measures of quality of life from a psychometric perspective by three different factor structure models. Three hundred and four students at National Taiwan University participated in this study. They completed the Satisfaction with Life Scale (SWLS, a global measurement for quality of life) and the WHOQOL-BREF (a domain-specific measurement for quality of life). Three models were specified to examine the relationships among scores of the SWLS and the WHOQOL-BREF. The first model was a common factor model in which scores of the SWLS and the WHOQOL-BREF were all influenced by a single factor. The second model was a correlated two-factor model in which scores of the SWLS were influenced by one factor and scores of the WHOQOL-BREF influenced by another factor, with these two factors being allowed to be correlated. The third model was a three-factor model, in which one factor (representing quality of life) influenced the scores of the SWLS and the WHOQOL-BREF, another factor (representing global approach) only influenced the scores of the SWLS, and yet another factor (representing domain approach) only influenced the scores of the WHOQOL-BREF. The results showed that the third model was the best, suggesting that global measures (the SWLS) and domain measures (the WHOQOL-BREF) did assess the same construct on quality of life, however, the measurement approaches they adopted (global or domain approach) also have substantial impact on the meaning of scores.