TEXT RETRIEVAL

_{Created by Vanessa}

A simple definition of TEXT RETRIEVAL is a computerised system which finds particular combinations of words in large bodies of text.

How do we measure the effectiveness of a search? There are two factors we look at:

1. Precision

2. Recall

PRECISION:this refers to the % of results that are actually useful.

RECALL: this refers to % of results you obtained from all possible relevant results.

An ideal search would have 100% precision and 100% recall. Realistically this is very unlikely, and a balance often has to be met between the two factors. By performing a wide search, users will obtain search results high in recall but low in precision. Conversely, a narrow search will be high in precision but recall will be sacrificed in the process.

For further information and a detailed examination of precision and recall effectiveness in respect of five major search engines please look here:

http://www.webology.ir/2005/v2n2/a12.html.