Learning to Quantify
Alejandro Moreo, Fabrizio Sebastiani · 2019
Quantification (also known as "supervised prevalence estimation" [2], or "class prior estimation" [7]) is the task of estimating, given a set σ of unlabelled items and a set of classes C = c1, . . . , c |C| , the relative frequency (or "prevalence") p(ci ) of each class ci C, i.e., the fraction of items in σ that belong to ci . When each item belongs to exactly one class, since 0 ≤ p(ci ) ≤ 1 and Í ci C p(ci ) = 1, p is a distribution of the items in σ across the classes in C (the true distribution), and quantification thus amounts to estimating p (i.e., to computing a predicted distribution p?).