Consideration of Thurstonian Scaling of Ratings Data

In the analysis of sensory data, the use of parametric statistics, specifically analysis of variance (ANOVA), is standard. However, such parametric analyses often make assumptions that are not valid. Recent advances have made available an alternative analysis that does not make these assumptions, specifically Thurstonian Scaling of Ratings Data (SoR). This study compared these two methods of analyses on a single dataset. To further clarify the differences between analyses, assessments of a subset of the stimuli were also made in a triangle task. Findings indicate that the differences between ANOVA and SoR are minimal, with SoR tending to be slightly more conservative. Regardless of analyses used, triangle tests were found to be superior at differentiating the stimuli. The d′ values determined using Thurstonian SoR did not agree with those determined with the triangle tests. Possible reasons for the discrepancy include boundary variance, actual strategy used during triangle tests, as well as other possible sources of variance.