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ORIGINAL ARTICLE |
1 Department of Occupational Medicine, Copenhagen University Hospital, Glostrup, Denmark
2 Department of Occupational Medicine, Herning Hospital, Herning, Denmark
Correspondence to:
Correspondence to:
Dr S Mikkelsen
Department of Occupational Medicine, Copenhagen University Hospital, Glostrup, Nordre Ringvej, DK 2600 Glostrup, Denmark; simi{at}glostruphosp.kbhamt.dk
Objective: To examine the validity and potential biases in self-reports of computer, mouse and keyboard usage times, compared with objective recordings.
Methods: A study population of 1211 people was asked in a questionnaire to estimate the average time they had worked with computer, mouse and keyboard during the past four working weeks. During the same period, a software program recorded these activities objectively. The study was part of a one-year follow-up study from 20001 of musculoskeletal outcomes among Danish computer workers.
Results: Self-reports on computer, mouse and keyboard usage times were positively associated with objectively measured activity, but the validity was low. Self-reports explained only between a quarter and a third of the variance of objectively measured activity, and were even lower for one measure (keyboard time). Self-reports overestimated usage times. Overestimation was large at low levels and declined with increasing levels of objectively measured activity. Mouse usage time proportion was an exception with a near 1:1 relation. Variability in objectively measured activity, arm pain, gender and age influenced self-reports in a systematic way, but the effects were modest and sometimes in different directions.
Conclusion: Self-reported durations of computer activities are positively associated with objective measures but they are quite inaccurate. Studies using self-reports to establish relations between computer work times and musculoskeletal pain could be biased and lead to falsely increased or decreased risk estimates.
Abbreviations: NUDATA, Neck and Upper extremity Disorders Among Technical Assistants; WPR, WorkPace Recorder
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J H Andersen, M Harhoff, S Grimstrup, I Vilstrup, C F Lassen, L P A Brandt, A I Kryger, E Overgaard, K D Hansen, and S Mikkelsen Computer mouse use predicts acute pain but not prolonged or chronic pain in the neck and shoulder Occup. Environ. Med., February 1, 2008; 65(2): 126 - 131. [Abstract] [Full Text] [PDF] |
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