It is possible to interpret precision and recall not as ratios but as probabilities:


Note that the random selection refers to a uniform distribution over the appropriate pool of documents; i.e. by "randomly selected retrieved document", we mean selecting a document from the set of retrieved documents in a random fashion. The random selection should be such that all documents in the set are equally likely to be selected.

Note that, in a typical classification system, the probability that a retrieved document is relevant depends on the document. The above interpretation extends to that scenario also (needs explanation).

Another interpretation for precision and recall is as follows. Precision is the average probability of relevant retrieval. Recall is the average probability of complete retrieval. Here we average over multiple retrieval queries.

সংগা (classification context)
Limitations as goals
সংগা (ইনফরমেশন রিট্রিভাল কনটেক্সট))
Probabilistic interpretation