Observer variability in posture assessment from video recordings: The effect of partly visible periods.
Observers rank partly visible postures on video frames differently than fully visible postures, but it's not clear if this is due to differences in observer perception. This study investigated the effect of posture visibility on between-observer variability in assessments of trunk and arm posture. Trained observers assessed trunk and arm postures from video recordings of 84 pulp mill shifts using a work sampling approach; postures were also categorized as 'fully' or 'partly' visible. Between-worker, between-day, and between-observer variance components and corresponding confidence intervals were calculated. Although no consistent gradient was seen for the trunk, right upper arm posture showed smaller between-observer variance when all observers rated a posture as fully visible. This suggests that, partly-visible data, especially when observers disagree as to the level of visibility, introduces more between-observer variability when compared to fully visible data. Some previously-identified differences in daily posture summaries may be related to this phenomenon.
Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, SE - 801 76 Gävle, Sweden; Centre for Health and Safety in Agriculture, College of Medicine, University of Saskatchewan, 104 Clinic Place PO Box 23, Saskatoon, Saskatchewan, S7N 2Z4, Canada. Electronic address: catherine.trask@usask.ca.
Catherine
C
Trask
Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, SE - 801 76 Gävle, Sweden. Electronic address: svenderik.mathiassen@hig.se.
Svend Erik
SE
Mathiassen
Collaborative Biostatistics Program, School of Public Health, University of Saskatchewan, Health Sciences building, 107 Wiggins Road, Saskatoon, Saskatchewan, S7N 5E5, Canada. Electronic address: mer521@mail.usask.ca.
Mehdi
M
Rostami
Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, SE - 801 76 Gävle, Sweden. Electronic address: marina.heiden@hig.se.
Marina
M
Heiden
D000328:Adult; D001132:Arm / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D066192:Manufacturing Industry; D008875:Middle Aged; D015588:Observer Variation; D016272:Occupational Health; D010209:Paper; D011187:Posture; D060726:Torso / Q000502:physiology; D014741:Video Recording; D055815:Young Adult
Exposure assessment; Inter-rater agreement; Observation; Posture; Pulp mill