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Diffstat (limited to 'Implementation.md')
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1 files changed, 39 insertions, 1 deletions
diff --git a/Implementation.md b/Implementation.md index e340ace..1a81e6f 100644 --- a/Implementation.md +++ b/Implementation.md @@ -39,6 +39,10 @@ set of documents, *Q* the set of queries, *tf* the function that counts the amount of times any of the query terms was found in that field and |*f*| the size of the field. +The formula assumes that relevance is more or less linear. The logarithm is +used because more occurrences of the same term are not as important as the +first occurrence. + ## Code We use three Python programs that: @@ -201,7 +205,8 @@ The system is agnostic with regards to the ranking function (BM25 or another method). ## Intermediate Results -These are the thirty most important fields as found by our measure: +These are the thirty most important fields as found by our measure when used on +the BM25 relevance scores: | Field | Score | Used by Nordlys | |------------------------------|----------:|:---------------:| @@ -246,5 +251,38 @@ In fact, we expect that many of the fields not used actually display similarities with fields that *are* indexed. For example, the `<dbo:abstract>` field will probably match because the title is repeated in the abstract. +We can perform the same analysis on the human assessments. This gives a rather +different list of fields: + +| Field | Score | Rank for BM25 | Used by Nordlys | +|-------------------------------|---------:|--------------:|:---------------:| +| `<dbp:pushpinMapCaption>` | 133.77 | 28 | ![][n] | +| `<dbp:foundation>` | 136.32 | 266 | ![][n] | +| `<dbp:imageCaption>` | 139.85 | 13 | ![][n] | +| `<dbp:bridgeName>` | 164.91 | 49 | ![][n] | +| `<dbp:imageFlag>` | 166.35 | 30 | ![][n] | +| `<dbp:mapCaption>` | 170.93 | 11 | ![][n] | +| `<dbo:foundingYear>` | 173.92 | 299 | ![][n] | +| `<dbp:producer>` | 186.37 | 12 | ![][n] | +| `<dbp:ground>` | 297.25 | 802 | ![][n] | +| `<dbp:title>` | 328.93 | 10 | ![][n] | +| `<dc:description>` | 332.05 | 8 | ![][n] | +| `<dbp:shortDescription>` | 334.79 | 9 | ![][n] | +| `<dbp:caption>` | 648.73 | 7 | ![][n] | +| `<foaf:givenName>` | 1436.74 | 21 | ![][y] | +| `<dbp:name>` | 1961.98 | 6 | ![][y] | +| `<foaf:name>` | 2086.67 | 5 | ![][y] | +| `<dbo:wikiPageWikiLinkText>` | 2897.51 | 4 | ![][y] | +| `<rdfs:label>` | 3483.06 | 3 | ![][y] | +| `<rdfs:comment>` | 12323.46 | 2 | ![][n] | +| `<dbo:abstract>` | 13002.74 | 1 | ![][n] | + +Based on this, one may want to try adding fields like `<dbp:caption>` to the +index. + +Conversely, this information can also be used to improve the relevance measure. +Apparently, `<dbp:ground>`, `<dbo:foundingYear>` and `<dbp:foundation>` are +quite relevant according to human assessors, but not at all according to BM25. + [y]: http://i.stack.imgur.com/iro5J.png [n]: http://i.stack.imgur.com/asAya.png |