Influence of Distribution of Odor Threshold among People and Bernoulli Trials on the Measurement of Odor Index by Triangle Test

Abstract

In the triangle test, which is used in the measurement of odors using the human sense of smell, there is a possibility that the measured odor indices might be affected by differences in olfactory ability among people. It is also necessary to consider the effect of a one-third probability of getting the correct answer by chance. The calculation procedures of the odor indices differ depending on whether ambient air or exhaust gas is used, so calculated values of the odor index differ even for the same data. In this study, we compared the two calculation procedures by computing the mean and standard deviation of the odor index, by using the distribution of odor threshold among people and the effect of accidental correct answers. From our results, the current correct answer rate of 0.58 used in the calculation procedure can be improved in the method for ambient air. It was also shown that the standard deviations of the odor indices from the calculation procedure of the method for exhaust gas were smaller than those for ambient air.