1. 1 Discussion Class 5 TREC

2. 2 Discussion Classes Format: Questions. Ask a member of the class to answer. Provide opportunity for others to comment. When answering: Stand up. Give your name. Make sure that the TA hears it. Speak clearly so that all the class can hear. Suggestions: Do not be shy at presenting partial answers. Differing viewpoints are welcome.

3. 3 Question 1: Objectives The TREC workshop series has four goals: (a)Encourage research in text based retrieval based on large test collections (b)Communication among industry, academia and government (c)Transfer of technology from research labs into products by demonstrating methodologies on real-world problems (d)Increase availability of appropriate evaluation techniques What does the ad hoc task contribute to each of these goals?

4. 4 Question 2: The TREC Corpus SourceSize# DocsMedian (Mbytes)words/doc Wall Street Journal, 87-8926798,732245 Associated Press newswire, 8925484,678446 Computer Selects articles24275,180200 Federal Register, 8926025,960391 abstracts of DOE publications184226,087111 Wall Street Journal, 90-9224274,520301 Associated Press newswire, 8823779,919438 Computer Selects articles17556,920182 Federal Register, 8820919,860396

5. 5 Question 2: The TREC Corpus (a)What characteristics of this data are likely to impact the results of experiments? (b)Explain the statement, "Disks 1-5 were used as training data." (c)Suppose that you were designing two search engines: (i) for use with a library catalog, (ii) for use with a Web search service. How does your data differ from the TREC corpus?

6. 6 Question 3: TREC Topic Statement Number: 409 legal, Pan Am, 103 Description: What legal actions have resulted from the destruction of Pan Am Flight 103 over Lockerbie, Scotland, on December 21, 1988? Narrative: Documents describing any charges, claims, or fines presented to or imposed by any court or tribunal are relevant, but documents that discuss charges made in diplomatic jousting are not relevant. A sample TREC topic statement

7. 7 Question 3: TREC Topic Statement (a)What is the relationship between TREC topic statements and queries? (b)Distinguish between manual and automatic methods of query generation. (c)Explain the process used by the manual methods. (d)Some of the results used a time limit (e.g., "limited to no more than 10 minutes clock time"). What was being timed?

8. 8 Question 4: Relevance Assessments (a)Explain the statement, "All TRECs have used the pooling method to assemble the relevance assessments." (b)How is relevance assessed? (c)What is the impact of some relevant documents being missed from the pool? (d)What is the problem of some relevant documents in the pool coming from only a single run? How serious is this?

9. 9 Question 5: Evaluation

10. 10 Question 5: What are: (a)The recall-precision curve? (b)The mean (non-interpolated) average precision? The report commented that, "two topics are fundamental to effective retrieval performance." What are they? How do the automatic tests differ from the manual?

11. 11 Question 6: The future (a)Why was TREC-8 the last year for the ad hoc task? (b)Does this mean that text-based information retrieval is now solved?