How Busy is Too Busy? Validation of the Dutch Integrated Workload Scale

The Integrated Workload Scale (IWS) is a subjective scale for real-time workload assessment. The nine anchor points of the IWS—ranging from “no workload” to “work too demanding”—capture the multidimensionality of the concept of workload by incorporating items reflecting time and effort in addition to workload and demand. Although originally designed for research with train dispatchers in the United Kingdom, the IWS has since been used to measure workload in other countries. In one of these countries, the Netherlands, the IWS has been translated into Dutch for use with train dispatchers. The aim of the present study was to validate the Dutch translation of the IWS. Dutch students and train dispatchers and English-language students were asked to rate the individual items of the IWS, in Dutch and English, respectively, on a scale from 0 (“no workload at all”) to 150 (“complete overload”). The mean ratings of items did not differ significantly between the groups, suggesting that the two versions of the IWS were interpreted similarly. Regression analyses showed that the scales were perceived as linear, with equidistant items. Additionally, alternate Dutch items were also rated as possible substitutions for some of the original items but were not found to significantly improve the linearity of the scale. The strong similarities of the Dutch IWS to the original IWS – including its multidimensional nature and the equidistant items – as well as the fact that train dispatchers and students gave similar ratings on the Dutch IWS suggest that it can reliably be used to assess subjective workload.