Absolute Magnitude Estimation and Relative Judgement Approaches to Subjective Workload Assessment

Two rating scale techniques employing an absolute magnitude estimation method, were compared to a relative judgement method for assessing subjective workload. One of the absolute estimation techniques used was an unidimensional overall workload scale and the other was the multidimensional NASA-Task Load Index technique. Thomas Saaty's Analytic Hierarchy Process was the unidimensional relative judgement method used. These techniques were used to assess the subjective workload of various of single- and dual-tracking conditions. The validity of the techniques was defined as their ability to detect the same phenomena observed in the tracking performance. Reliability was assessed by calculating test-retest correlations. Within the context of the experiment, the Saaty Analytic Hierarchy Process was found to be superior in validity and reliability. These findings suggest that the relative judgement method would be an effective addition to the currently available subjective workload assessment techniques.