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Essentially, a JEM comprises a list of levels of exposure to a variety of harmful (or potentially harmful) agents for selected occupational titles. In large population-based epidemiological studies, JEMs may be used as a quick and systematic means of converting coded occupational data (job titles) into a matrix of possible exposures, obviating the need to assess each individual's exposure in detail.
Assessing exposure by title is less costly than looking at individual cases. JEMs may also reduce differential information bias that might occur when evaluating exposure for individuals from medical records in which their jobs are apparent.
Variability of exposure within occupational classes in different workplaces, countries, or throughout time is commonly not taken into account, which can result in nondifferential exposure misclassification.
- Kauppinen TP, Mutanen PO, Seitsamo JT. Magnitude of misclassification bias when using a job-exposure matrix. [Internet]. Scandinavian Journal of Work, Environment & Health 1992 Apr;18(2):105-112.[cited 2011 Dec 16] Available from: http://www.sjweh.fi/show_abstract.php?abstract_id=1604