An effect size index for comparing two independent alpha coefficients

Since Cronbach proposed the α coefficient in 1951, researchers have contributed to the derivation of its sampling distribution and the testing of related statistical hypotheses. Yet, there has been no research on effect size index relevant to coefficient α to our knowledge. Considering the importance of effect size in understanding quantitative research findings, we therefore developed an effect size index Δ for the comparison of two independent αs with equal test length based on the asymptotic distribution of under the assumptions of normality and compound symmetry. Simulations indicated that the index was applicable when the sample size was at least 100. The robustness of the derived index when the required assumptions were violated was also explored. It is suggested that the index should be applicable in most cases of unequal test lengths and could be extended to non‐normally distributed component scores. Moreover, a small simulation was conducted to explore the behaviour of Δ with correlated errors, a frequently studied situation violating the assumption of compound symmetry. The proposed index was found to be robust unless a large number of highly correlated errors were present in the data.     

The effects of perceived pressures on managerial and nonmanagerial scientists and engineers

The two major purposes of the present study were (1) to empirically investigate the effects of excessive pressures perceived by Ph.D.-level scientists and engineers employed in a large multidivisional energy R&D laboratory on work attitudes and performance; and (2) to test the proposition that scientists with managerial responsibilities perceive more pressures and strains than do those with no such duties. Results indicated that the pressured scientists perceived more role strain and a less positive climate, were less satisfied, and received lower performance evaluations from their supervisors than non-pressured ones. No differences were found in the perception of pressures between the managerial and nonmanagerial scientists, although the managers reported a more positive climate and higher satisfaction than did nonmanagers. The implications of these findings with regard to management practice (i.e., dual ladders) and future research on stress among this occupational group were briefly discussed.