( | . | is the counting measure)

There is a functional relationship between all three involving a parameter called generality (G) which is a measure of the density of relevant documents in the collection. The relationship is:

For each request submitted to a retrieval system one of these tables can be constructed. Based on each one of these tables a precision-recall

Figure 7.1. The precision–recall curves for two queries. The ordinals indicate the values of the control parameter

* For a derivation of this relation from Bayes' Theorem, the reader should consult the author's recent paper on retrieval effectiveness^[10].