Paper Title
Extent of Irrationality of The Consumer: Combining the Critical Cost Efficiency and Houtman-Maks Indices

Abstract
We combined the Critical Cost Efficiency Index and the Houtman-Maks Indexto evaluate the consistency of subjects in choosing within a set of data frombudgets. We show, using an online experiment from the general population, that by simply allowing subjects one significant mistake (by removing the worstobservation), the mean Critical Cost Efficiency Index for a set of choices increasesby 6 percentage points. Furthermore, we find that by excluding the worstobservation per subject, the proportion of subjects wasting 5% or less of theirbudget increases from 45% to 64%. The highest improvement in terms of efficiencywas seen among subjects who were retired and aged 65+ years, which indicatesthat their low level of efficiency is largely due to a single mistake. Keywords - Critical Cost Efficiency Index, Houtman-MaksIndex, Socio-economic groups, observation