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Open Access Research article

Effort, reward and self-reported mental health: a simulation study on negative affectivity bias

Marc Arial1* and Pascal Wild12

Author Affiliations

1 Institute for Work and Health, Lausanne University and Geneva University, Bugnon 21, CH-1011 Lausanne, Switzerland

2 PW Statistical Consulting, 56, avenue Paul Déroulède, 54520 LAXOU- France

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BMC Medical Research Methodology 2011, 11:121  doi:10.1186/1471-2288-11-121

Published: 24 August 2011

Abstract

Background

In the present article, we propose an alternative method for dealing with negative affectivity (NA) biases in research, while investigating the association between a deleterious psychosocial environment at work and poor mental health. First, we investigated how strong NA must be to cause an observed correlation between the independent and dependent variables. Second, we subjectively assessed whether NA can have a large enough impact on a large enough number of subjects to invalidate the observed correlations between dependent and independent variables.

Methods

We simulated 10,000 populations of 300 subjects each, using the marginal distribution of workers in an actual population that had answered the Siegrist's questionnaire on effort and reward imbalance (ERI) and the General Health Questionnaire (GHQ).

Results

The results of the present study suggested that simulated NA has a minimal effect on the mean scores for effort and reward. However, the correlations between the effort and reward imbalance (ERI) ratio and the GHQ score might be important, even in simulated populations with a limited NA.

Conclusions

When investigating the relationship between the ERI ratio and the GHQ score, we suggest the following rules for the interpretation of the results: correlations with an explained variance of 5% and below should be considered with caution; correlations with an explained variance between 5% and 10% may result from NA, although this effect does not seem likely; and correlations with an explained variance of 10% and above are not likely to be the result of NA biases.