Statistically accurate evidence of improved error rate by pairwise comparisons

A statistical experiment was designed to check whether the pairwise comparisons method, introduced by Thurstone in 1927, can really improve the accuracy of estimation of stimuli. This method was compared with direct rating. The experiment was designed and implemented to minimize statistical bias. Randomly generated bars were used since everyone is an expert on estimating lengths. The statistical analysis favoured the pairwise comparisons method. The obtained results are decisive; more than a 300% improvement in accuracy was gained with at least 10(-4) level of confidence.