A concentration indicator of the frequencies on the extremes for the ordinal categorial variables based on judgments

The conversion problem on the metric scale of the judgments expressed towards the products or the services can be solved searching the latent variable, that is always the normal standard. Sometimes, particularly when the frequencies are concentrated on the left extreme or the right extreme of the distribution, the assumption of the normal brings to opposite results. We have used, in the above mentioned circumstances, the exponential, negative or positive, suitably standardized, obtaining more acceptable results and more adjusted to the observed distribution structures. In this note we have proposed , into the range –1 and +1, an indicator that assists in the selection among the exponential negative or positive and the normal. Its validity has been examined by some examples, that included a number rather diffuse of peculiar cases.