Relevance as a percentage (originating from ​Nationaal Georegister)

Date	2009/09/03
Contact(s)	​Heikki Doeleman
Last edited	Timestamp
Status	Proposed for vote
Assigned to release	2.5
Resources	The work may be done in the NGR project

Overview

In standard GeoNetwork search results can be ordered by relevance. This is based on the relevance score that the Lucene search engine gives to each item in the search results. However it is not shown to the user what the relevance score for each result *is* or how they compare between each other.

Proposal Type

• Type: GUI change, Core change
• App: GeoNetwork
• Module: Search results, Search engine

Links

• Email discussions: on geonetwork-devel: ​Proposals to include NGR functionality to GeoNetwork trunk
• IRC discussions: ​September 1st, 2009 on GeoNetwork's IRC channel

Voting History

• None as yet

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Motivations

The motivations for these changes are :

1. Better usability

Proposal

In standard GeoNetwork search results can be ordered by relevance. This is based on the relevance score that the Lucene search engine gives to each item in the search results. However it is not shown to the user what the relevance score for each result *is*.
In ​NGR the relevance score is displayed with each search result. Because the Lucene score is an unattractive float between 0 and 1, the relevance score is normalized such that the highest score from the search results is set to 100, and all other results' scores are calculated relative to that.

This proposal is somewhat controversial, as people may feel that scoring "100%" to the highest ranking result is misleading. An alternative could be to simply show the (rounded) Lucene relevance ranking. And it appears that many people poorly understand the nature of Lucene's relevance ranking, thinking that the calculated relevance of one search request's result could be compared to that of another search request's result (it *can't*) or that it naturally tallies with people's innate idea of what is and what isn't relevant, which is of course also not always the case. So if you don't like it, simply vote against this!

Backwards Compatibility Issues

none

Risks

Participants

• As above