Daily self-reports resulted in information bias when assessing exposure duration to computer use.
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.
Chang
Che-Hsu Joe
CH
Department of Environmental Health, Harvard University, Boston, Massachusetts, USA.
Menéndez
Cammie Chaumont
CC
Robertson
Michelle M
MM
Amick
Benjamin C
BC
Johnson
Peter W
PW
del Pino
Rosa J
RJ
Dennerlein
Jack T
JT
D000328:Adult; D015982:Bias; D003625:Data Collection / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008838:Microcomputers; D016273:Occupational Exposure / Q000706:statistics & numerical data*; D057566:Self Report; D012984:Software; D018709:Statistics, Nonparametric; D013647:Task Performance and Analysis; D055815:Young Adult