(in German)

The Work Ability Index (WAI) is an established instrument for assessing work ability. It was developed under the controversial assumption of one-dimensionality as an unweighted sum score. The objectives of this work are the construct validation of the WAI, taking into consideration the until now unexamined measurement invariance for various subgroups, and the weighted scoring and validation of individual values. The data come from a representative sample of the working population in Germany (N = 3,968). Using confirmatory factor analysis, dimensionality and measurement invariance of the WAI were examined for sex and 3 age groups. Convergence validity was investigated by means of correlation analysis using the Short-Form-12 Health Survey and the Norwegian Function Assessment Scale. The results support an assumption of two-dimensionality along with scalar measurement invariance for the tested subgroups. The weighted sum scores were derived from the results on the factorial structure and convergent validity for the examined instruments was found. Thus, work ability in the WAI is represented by the factors of subjective work ability and resources, as well as the health conditions.

Please download the complete report "The construct validity of the Work Ability Index based on a representative sample of workers in Germany" (in German only).