GMAP

Synonyms

Geometric mean average precision

Definition

The Geometric Mean Average Precision (GMAP) is the geometric mean of the average precision values for an information retrieval system over a set of n query topics. GMAP is expressed as follows (from [1]):

$$ \mathrm{GMAP}=\sqrt[n]{{\displaystyle \prod_n{\mathrm{AP}}_n}} $$

where AP represents the Average Precision value for a given topic from the evaluation set of n topics. Please refer to the entry on Average Precision for the complete definition of AP. An alternate calculation method expresses GMAP as an arithmetic mean of logs (also from [1]):

$$ \mathrm{GMAP}= \exp \frac{1}{n}{\displaystyle \sum_n \log {\mathrm{AP}}_n} $$

Key Points

The Geometric Mean Average Precision evaluation metric was first introduced in the Robust track at the 2004 NIST Text Retrieval Conference (TREC). A stated goal of the robust track was to examine and evaluate information retrieval systems with a view towards achieving consistently good performance...