This study examined the accuracy with which trained and conditioned females could set Maximum Acceptable Weights (MAWs) using ratio estimation. Examined were two lifting ranges, floor-to-knuckle and knuckle-to-shoulder, and four lift frequencies (lifts every 9-, 20-, 60-, and 120-seconds). In each of the eight conditions subjects set the MAW using the method of adjustment. Immediately after the MAW had been set, the task was changed, performed for a few cycles, and rated using ratio estimation. This rating was used to establish an estimated MAW for the second lifting task. On a later day, the MAW was set for the second task using the method of adjustment and the MAW for the original task estimated with ratio estimation. This allowed comparison of the accuracy of MAWs set by psychophysical and ratio estimation methods as affected by the frequency and lifting zone of the standard task. Consistent with previous research there were significant effects on the MAW due to frequency of lift and the lift range. Also, and importantly, there were no significant differences between MAWs set by ratio estimation and by the traditional method of adjustment (p>0.6). This indicates that ratio estimation is an accurate method to quickly establish MAWs for a variety of lifting tasks. This indicates that MAWs for entire classes of lifting tasks can be quickly and accurately determined with ratio estimation.
DGQR estimation for interval censored quantile regression with varying-coefficient models
