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Exercising these ideas

Exercising these ideas. You have a description of each item in a small collection. (30 web sites) Assume we are looking for information about boxers, a type of dog. List the items that are relevant to this information need. (If it is impossible to tell, as with #9, mark it not relevant.)

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Exercising these ideas

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  1. Exercising these ideas • You have a description of each item in a small collection. (30 web sites) • Assume we are looking for information about boxers, a type of dog. • List the items that are relevant to this information need. (If it is impossible to tell, as with #9, mark it not relevant.) • Rq = { } • Assume that an unspecified search system has returned a ranked result as follows: • (1, 4, 6, 8, 10, 12, 15, 16, 17, 18, 20, 23,26, 28, 30) • Show the ranking for the query as done on page 76. • Plot the precision vs. recall curve

  2. Exercise, continued • We do a second query against the same collection. This time we are interested in the Boxer rescue organizations. • Rq = { } • Ranked result = (4, 6, 7, 10, 11, 15, 16, 17, 18, 19, 22, 23, 25, 28, 29) • Calculate the average precision at recall level 3 for these two queries.

  3. More exercise • We redo the first query, using a new search algorithm. The ranked result is now this: • (4, 5, 6, 7, 8, 10, 11, 15, 16, 17, 18, 20, 23, 28, 29) • Produce the average recall vs. precision figures for these two algorithms. How would you describe the performance? • We redo the second query using the new search algorithm. The ranked result is this: • (7, 10, 11, 15, 17, 18, 19, 21, 23, 24, 26, 28, 29, 30)

  4. Precision Histogram

  5. For each of the four searches, what is the R-precision? • Use a precision histogram to compare these two algorithms for the two queries shown. • Calculate the harmonic mean at document 5 in the rankings, using the first query and repeating for each algorithm. • Calculate the E measure for algorithm 1 using query 1 and a moderate preference for recall rather than precision.

  6. |Rk| Coverage = ------ |U| |Ru| Novelty = --------------- |Ru| + |Rk| Collection Answer Set |A| Relevant docs |R| Relevant docs unknown to the User which were retrieved |Ru| Relevant docs known to the User |U| Relevant docs known to the User which were retrieved |Rk|

  7. Assume that the even number elements in the collection are known to the user. • Calculate the coverage ratio for algorithm 1 on search 1 • Calculate the novelty ratio for the same algorithm and search

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