Given that our objective is to mimic the annotation process, we seek to estimate the proportion of documents in the target corpus expected to be categorized into each of the K categories, if we had an unlimited budget and full access to the target corpus at the time of annotation.
we wish to estimate q (T ) , which we define as: (2) Given a set of documents sampled from the source corpus and L applications of the annotation function, we can obtain, at some cost, a labeled training corpus of L documents, i.e., D (train)  .