Daily self-reports resulted in information bias when assessing exposure duration to computer use

Am J Ind Med. 2010 Nov;53(11):1142-9. doi: 10.1002/ajim.20878.


Background: Self-reported exposure duration to computer use is widely used in exposure assessment, and this study examined the associated information bias in a repeated measures setting.

Methods: For 3 weeks, 30 undergraduate students reported daily cumulative computer-use duration and musculoskeletal symptoms at four random times per day. Usage-monitor software installed onto participant's personal computers provided the reference measure. We compared daily self-reported and software-recorded duration, and modeled the effect of musculoskeletal symptoms on observed differences.

Results: The relationships between daily self-reported and software-recorded computer-use duration varied greatly across subject with Spearman's correlations ranging from -0.22 to 0.8. Self-reports generally overestimated computer use when software-recorded durations were less than 3.6 hr, and underestimated when above 3.6 hr. Experiencing symptoms was related to a 0.15-hr increase in self-reported duration after controlling for software-recorded duration.

Conclusions: Daily self-reported computer-use duration had a weak-to-moderate correlation with software-recorded duration, and their relationship changed slightly with musculoskeletal symptoms. Self-reports resulted in both non-differential and differential information bias.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Bias*
  • Data Collection / methods
  • Data Collection / statistics & numerical data*
  • Female
  • Humans
  • Male
  • Microcomputers*
  • Occupational Exposure / statistics & numerical data*
  • Self Report*
  • Software
  • Statistics, Nonparametric
  • Task Performance and Analysis
  • Young Adult