Original article

Scand J Work Environ Health 2008;34(2):113-119    pdf


Test–retest reliability and validity of self-reported duration of computer use at work

by IJmker S, Leijssen JNM, Blatter BM, van der Beek AJ, van Mechelen W, Bongers PM

Objectives The aims of this study were to evaluate the test–retest reliability and the validity of self-reported duration of computer use at work.

Methods Test–retest reliability was studied among 81 employees of a research department of a university medical center. The employees filled out a web-based questionnaire twice with an in-between period of 14 days. Validity was studied among a group of 572 office workers who participated in an epidemiologic field study. A software program recorded the duration of computer use at work during the 3 months preceding the questionnaire.

Results The percentages of agreement for test–retest reliability were 75% [95% confidence interval (95% CI) 64–84] for total computer use and 67% (95% CI 55–77) for mouse use. The percentages of agreement between self-report and registration were 18% (95% CI 15–21) for total computer use and 16% (95% CI 13–19) for mouse use. Misclassification was mainly nondifferential in nature, since all of the evaluated subgroups showed at least 75% misclassification.

Conclusions The use of self-reports lead to the misclassification of exposure to computer use for more than 80% of all persons. This misclassification is predominantly nondifferential in nature and can only partly be explained by limited test–retest reliability.

This article refers to the following text of the Journal: 2005;31(2):122-131