Modifying search result ranking based on implicit user feedback

1. A computer-implemented method comprising:

determining a first number representing a count of longer views of a document following selections of search results, where the search results reference the document in response to submissions of a search query to a search engine;

determining a second number representing a count of shorter views of the document following the selections of the search results, where the search results reference the document in response to submissions of the search query;

determining a measure of relevance for the document with respect to the search query based on a ratio between the first number and the second number; and

outputting the measure of relevance to a ranking engine for ranking of search results, including new search results referencing the document, for a new search responsive to a new submission of the search query.

2. The method of claim 1 , wherein determining the measure of relevance comprises dividing the first number by a count of total views of the document.

3. The method of claim 1 , further comprising:

tracking individual selections of the search results referencing the document within the context of the search query for which the search results are returned;

weighting document views resulting from the selections based on viewing length information to produce weighted views of the document result; and

combining the weighted views of the document result to determine the first number.

4. The method of claim 3 , wherein determining the measure of relevance comprises dividing the first number by the second number.

5. The method of claim 3 , wherein the weighting comprises applying a continuous function to the document views resulting from the selections.

6. The method of claim 3 , wherein the weighting comprises applying a discontinuous function to the document views resulting from the selections.

7. The method of claim 6 , wherein applying the discontinuous function comprises:

classifying the individual selections of the document result into viewing time categories; and

assigning weights to the individual selections based on results of the classifying.

8. The method of claim 3 , wherein the weighting comprises weighting the document views based on the viewing length information in conjunction with a viewing length differentiator.

9. The method of claim 8 , wherein the viewing length differentiator includes a factor governed by a determined category of the search query, and the weighting comprises weighting the document views based on the determined category of the search query.

10. The method of claim 8 , wherein the viewing length differentiator includes a factor governed by a determined type of a user generating the individual selections, and the weighting comprises weighting the document views based on the determined type of the user.

11. A system comprising:

one or more computers; and

a computer program product, encoded on a non-transitory computer-readable medium, operable to cause the one or more computers to perform operations comprising:

determining a first number representing a count of longer views of a document following selections of search results, where the search results reference the document in response to submissions of a search query to a search engine;

determining a second number representing a count of shorter views of the document following the selections of the search results, where the search results reference the document in response to submissions of the search query;

determining a measure of relevance for the document with respect to the search query based on a ratio between the first number and the second number; and

outputting the measure of relevance to a ranking engine for ranking of search results, including new search results referencing the document, for a new search responsive to a new submission of the search query.

12. The system of claim 11 , wherein determining the measure of relevance comprises dividing the first number by a count of total views of the document.

13. The system of claim 11 , the operations further comprising:

tracking individual selections of the search results referencing the document within the context of the search query for which the search results are returned;

weighting document views resulting from the selections based on viewing length information to produce weighted views of the document result; and

combining the weighted views of the document result to determine the first number.

14. The system of claim 13 , wherein determining the measure of relevance comprises dividing the first number by the second number.

15. The system of claim 13 , wherein the weighting comprises applying a continuous function to the document views resulting from the selections.

16. The system of claim 13 , wherein the weighting comprises applying a discontinuous function to the document views resulting from the selections.

17. The system of claim 16 , wherein applying the discontinuous function comprises:

classifying the individual selections of the document result into viewing time categories; and

assigning weights to the individual selections based on results of the classifying.

18. The system of claim 13 , wherein the weighting comprises weighting the document views based on the viewing length information in conjunction with a viewing length differentiator.

19. The system of claim 18 , wherein the viewing length differentiator includes a factor governed by a determined category of the search query, and the weighting comprises weighting the document views based on the determined category of the search query.

20. The system of claim 18 , wherein the viewing length differentiator includes a factor governed by a determined type of a user generating the individual selections, and the weighting comprises weighting the document views based on the determined type of the user.