Effect of sampling interval on the reliability of ergonomic analysis using the Ovako working posture analysing system (OWAS)

- Defining a sampling strategy is as least as important as the assessment method.
- Sampling interval has a significant effect on the reliability of sampling.
- Smaller sampling intervals lead to better reliability of sampling.

In industry, the Ovako working posture analysing system (OWAS) is applied using different sampling intervals. However, it has not yet been established what influence the sampling interval has on the reliability of the data collection. For this purpose, the sampling interval of an existing ergonomic analysis of working postures using OWAS with 20,601 observations was varied between 2 and 90 s to investigate the effects of deviation from the original sampling interval of 1 s. Based on these comprehensive industrial data, which was statistically analyzed with regression analyses, it can be concluded that in the ergonomic analysis of working postures using OWAS, direct observations should have a sampling interval of 20 s, and video-based observations should have a sampling interval of 10 s or less.Relevance to industryThe Ovako working posture analysing system (OWAS) is a practical and frequently selected method for the ergonomic analysis and evaluation of working postures. However, the selection of a suitable method is as least as important as the definition of a sampling strategy providing reliable values obtained through observation. For this reason we investigated the effect of the sampling interval and recommend using 20 s for direct observations and 10 s or less for video-based observations.