(All reference numbers are from Schnall PL, Landsbergis PA, Baker D. Job strain and cardiovascular disease. Annual Review of Public Health 1994;15:381-411.)
Self report bias is a potential problem in many "job
strain" studies, since exposure has often been assessed
through questionnaires completed by study participants.
Self-reports may be inaccurate descriptions of job
characteristics or may be biased by personality traits such as
"negative affectivity". Concerns have also been raised
about the need for more objective measures of "job
strain" in intervention studies.
Therefore, in 13 "job strain" studies, researchers
employed an analytic technique to overcom self-report bias and
obtain more objective measures of job characteristics - the
imputation of average scores for a particular job title to
individuals in that job title. The average job-title score, free
of the individual's subjective assessment, then predicts outcome
for the individual. However, while this strategy is often
presented as desirable, it developed in the U.S.A.. because of a
lack of databases containing both job characteristics data and
health data - a weakness of past research. Large within variance
exists in job characteristics (55% of reliable variance for
latitude, and 93% for demands), since job titles such as nurse,
machinist, secretary or teacher are somewhat heterogenous in
skill levels, autonomy, or demands (102). As a result, in the
U.S. studies, mean scores of job characteristics are adjusted for
demographic covariates (e.g., age, race, education, marital
status, region, urban vs. rural, and self-employment status) in
the HANES 1 (59) when imputed to an individual participant (102).
Despite this adjustment, the imputation strategy introduces
(non-differential) misclassification and a bias towards the null.
Thus, positive findings using the imputation method (4, 5, 36,
59, 68, 81, 109) provide strong support for the model, while
negative studies may result, in part, from loss of power.
However, individual level job data and health data clearly need
to be obtained in future research.
For more information regarding this site, e-mail us at: cse@workhealth.org
*** This site is best viewed using Internet Explorer 3.0; some other browsers may not support the tables presented on this site***