**Recall and Precision**

The most important parameters used for evaluating an indexing system are: Recall and Precision.

**Recall**

The term recall refers to a measure of whether or not a particular item is retrieved or the extent to which the retrieval of wanted items occur.

Recall ratio is nothing but the proportion of relevant items retrieved and thus, it is a measure of the completeness of a search in an index file

The recall ratio has been variously called as hit rate, sensitivity, and conditional probability of a hit.

The general formula for calculation of recall ratio

Number of relevant

Recall Ratio =............................... ….... * 100

Total number of relevant

**Precision**

The term precision relates to the ability of an indexing system not to retrieve irrelevant items

Precision ratio is nothing but the proportion of retrieved items that are relevant

The precision ratio is sometimes referred to as a relevance ratio.

formula for calculation of precision ratio

Number of relevant

Precision Ratio =................................ ….......* 100

Total number