A subsequent query by the same searcher that is different from any of the searcher's previous queries is a modified query . A unique query refers to a query that is different from all other queries, regardless of the searcher. Of course, one can have various sub-components of these classifications. At the query level of analysis, one is generally interested in determining query length, query complexity and failure rate. Query length is measured in terms.
Query complexity examines the query syntax.
Query syntax includes the use of advanced searching techniques such as Boolean operators, phrased searching and stemming. These symbols are referred to as term modifiers and are also a component of query syntax. The failure rate is presented and is defined as deviation from the published rules of the IR system. A term is defined as a string of characters separated by some delimiter such as a space, colon or period. The researcher decides which delimiter to utilize.