Comparison of the observer, single-frame video and computer vision hand activity levels.

Observer, manual single-frame video, and automated computer vision measures of the Hand Activity Level (HAL) were compared. HAL can be measured three ways: (1) observer rating (HAL O ), (2) calculated from single-frame multimedia video task analysis for measuring frequency (F) and duty cycle (D) (HAL F ), or (3) from automated computer vision (HAL C ). This study analysed videos collected from three prospective cohort studies to ascertain HAL O , HAL F , and HAL C for 419 industrial videos. Although the differences for the three methods were relatively small on average (<1), they were statistically significant ( p < .001). A difference between the HAL C and HAL F ratings within ±1 point on the HAL scale was the most consistent, where more than two thirds (68%) of all the cases were within that range and had a linear regression through the mean coefficient of 1.03 ( R 2 = 0.89). The results suggest that the computer vision methodology yields comparable results as single-frame video analysis. Practitioner summary: The ACGIH Hand Activity Level (HAL) was obtained for 419 industrial tasks using three methods: observation, calculated using single-frame video analysis and computer vision. The computer vision methodology produced results that were comparable to single-frame video analysis.