Precision at n
- Nick CraswellAffiliated withMicrosoft Research Cambridge
In an information retrieval system that retrieves a ranked list, the top-n documents are the first n in the ranking. Precision at n is the proportion of the top-n documents that are relevant.
The value of n can be chosen based on an assumption about how many documents the user will view. In Web search a results page typically contains ten results, so n = 10 is a natural choice. However, not all users will use the scrollbar and look at the full top ten list. In a typical setup the user may only see the first five results before scrolling, suggesting Precision at 5 as a measure of the initial set seen by users. It is the document at rank 1 that gets most user attention, because this is the document that users view first, suggesting the use of Precision at 1 (which is equivalent to Success at 1).
It is possible to calculate p ...
Reference Work Entry Metrics
- Precision at n
- Reference Work Title
- Encyclopedia of Database Systems
- pp 2127-2128
- Print ISBN
- Online ISBN
- Springer US
- Copyright Holder
- Springer Science+Business Media, LLC
- Additional Links
- Industry Sectors
- eBook Packages
- Editor Affiliations
- 1. College of Computing, Georgia Institute of Technology
- 2. Database Research Group David R. Cheriton School of Computer Science, University of Waterloo
- Nick Craswell (1)
- Author Affiliations
- 1. Microsoft Research Cambridge, Cambridge, UK
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