Dear Friends,

We often talk and write about objective and subjective probabilities, about objective and subjective measures of uncertainty. However, at a recent conference on uncertainty, Yakov Ben-Haim made an important observation -- based on his experience of working on applications with colleagues from many different areas.

His experience is that in many application areas, the word “subjective” has a negative connotation: it means unjustified estimates based on gut feeling only, prone to bias and wild variations.

Such gut-feeling-based estimations sometimes happen, but mostly, when we talk about “subjective”, we mean judgmental estimates, estimates which are not just coming out of gut feeling, but which can be usually provided with some justification. For example, if we estimate to what extent someone is young (one of Zadeh’s original examples) we can usually explain the degree we assign to “youngness” of an individual by referring to features which are present and which are typical young age – and features of this individual which are more typical for mature-age folks.

For example, subjective probability often means simply probability that is not coming from the analysis of frequency, but from expert estimates.

Yakov’s recommendations is to use words like “judgmental” (or “expert-based”) instead of “subjective” in such situations, especially when working on applications – and applications are the main goal of uncertainty studies in the first place.