In summary, the sign of the coefficient relating intelligence to IPJC provides a critical test of the validity of IPJC as a measure of job complexity.
One the one hand--if IPJC is influenced by job attitudes--the effect of age on IPJC should be negative.
We chose to analyse the interviews conducted in 1982, since they contained a measurement of IPJC.
Since these items measure a unidimensional construct (Aldag, Barr, & Brief, 1981; Drasgow & Miller, 1982), most appropriately labelled job complexity (Hackman & Oldham, 1980; Stone & Gueutal, 1985), the participants' ratings were average to construct an overall index of IPJC.
The coefficients relating education to IPJC and to job satisfaction were non-significant (p [is greater than] .
3, the crucial parameters of the model--those relating intelligence to IPJC and to job satisfaction--provide strong evidence for the validity of IPJC as a measure of job complexity.
In particular, whereas intelligence directly affects both DOT complexity and IPJC, education affects only DOT complexity (its effect on IPJC is completely mediated by DOT complexity).
Since the effect of age on job satisfaction is negative, this positive effect is consistent with the idea that IPJC is a valid measure of job complexity, and is not merely a measure of job attitudes.
3, except that the direct effect of age on IPJC was significantly positive (p [is less than] .
Since the effect of intelligence on job satisfaction is negative, this positive effect of intelligence on IPJC is inconsistent with the notion that IPJC is merely a reflection of job satisfaction--that people's ratings of job characteristics are simply a reflection of their attitudes towards their work.
The results of the paper also suggest that DOT complexity and IPJC measure two different, yet related, constructs, and that IPJC is a valid measure of job complexity even when occupation is held constant.
In particular, our results show that within-occupations, intelligence, but not education, plays a major role in gravitation towards more complex jobs, at least when the complexity of these jobs is assessed by IPJC, whereas between-occupations the role of education and intelligence in the gravitation process is about the same.