Cost efficiency comparison of four video-based techniques for assessing upper arm postures

Abstract

The cost efficiency of four video-based techniques for assessing upper arm postures was compared. Work sampling techniques were in general more cost efficient than continuous observations since they were labour-saving. Whilst a labour cost dominated the comparison, 'hidden costs', bias and measurement strategy also influenced this dominance.

Cost-efficient assessment of biomechanical exposure in occupational groups, exemplified by posture observation and inclinometry

“…This is opposite to what has been reported in a study of hairdressers' upper-arm postures, where video observers overestimated inclination angles (21). A lab-based study identified an observation over-estimation in higher exposure ranges for trunk flexion when compared to opto-electric tracking (51); validation studies of neck flexion also showed observations to over-estimate when compared to an inclinometer (52).…”

“…Thus, by definition, the results obtained by inclinometry were taken to be unbiased (B=0), and the bias, B, of the results obtained by observation was calculated as the difference between mean exposures obtained by observation and the corresponding results according to inclinometry. The combined precision and bias performance of each posture assessment method was calculated as the inverse of the RMSE μ (19,21), which is thus, by definition, equal to 1/ for inclinometry in the present case.…”

“…Observation has long been believed to represent a middle ground in that they are more objective than self-reports (19,27,29), yet less consistent than direct measurements. The suspected inferior precision associated with using observational methods would mainly be a result of variability introduced by within-and betweenobserver differences in opinions when viewing the same posture (21,(32)(33)(34). At the same time, observations have been anecdotally claimed to be cheaper in use than direct measurements (27).…”

“…However, there have been few comprehensive efforts to report the empirical costs of biomechanical exposure assessment, and these preliminary efforts did not include any information on the quality or statistical properties of exposure information delivered (35)(36)(37). Recently some studies have combined empirical costs and precision of occupational exposure estimates, although these have addressed cost efficiency in general terms (20), or have focused on a narrow assessment of cost and compared sampling or analysis strategies just within a single method [in casu, observation; (19,21)]. …”

“…Although these articles have furthered inquiry into efficient exposure assessment from a statistical point of view, they have been criticized for rarely acknowledging the actual costs of exposure assessment. Thus, a 2010 systematic review of literature focusing on cost-efficient collection of exposure data (18) found only nine studies dealing with the trade-off between statistical performance and monetary resources invested in obtaining that performance, even if some studies have appeared after 2010 (19)(20)(21). Only some of the publications identified in the 2010 review dealt specifically with occupational or environmental exposures (7,(22)(23)(24)(25)(26); only two of these included empirical data to illustrate cost and efficiency (24,26), and none were devoted to assessment of biomechanical exposure.…”