Searching techniques


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Searching techniques

  1. 1. Searching Techniques J.A.Amaraweera Lecturer MCHE [email_address]
  2. 2. Contents <ul><li>How to find Online information? </li></ul><ul><li>What is a search engine? </li></ul><ul><li>What is a Subject Directory? </li></ul><ul><li>Subject Gateways </li></ul><ul><li>How do I prepare search? </li></ul><ul><li>Effective Online search strategies </li></ul><ul><li>Information resources Online </li></ul><ul><li>Judging what you find </li></ul>
  3. 3. How to find Online information? <ul><li>Guessing the URL ( U niform R esource L ocator) </li></ul><ul><li>Using a Search Engine (General, Subject, Meta) </li></ul><ul><li>Using a Web directory, Subject Gateway </li></ul>
  4. 4. What is a search engine? <ul><li>Definition: </li></ul><ul><li>A search engine is a searchable database of Internet files collected by a computer program (called a crawler, robot, worm, spider). Indexing is created from the collected files, e.g., title, full text, size, URL, etc. There is no selection criteria for the collection of files, though evaluation can be applied to ranking schemes that return the results of a query. </li></ul>
  5. 5. What is a subject directory? <ul><li>Definition: </li></ul><ul><li>A subject directory is a service that offers a collection of links to Internet resources submitted by site creators or evaluators and organized into subject categories. Directory services use selection criteria for choosing links to include, though the selectivity varies among services. Most directories are searchable. </li></ul>
  6. 6. Search engines <ul><li>Huge databases </li></ul><ul><li>Large amount of material </li></ul><ul><li>Databases are updated at a variable rate </li></ul><ul><li>Emphasis quantity over quality </li></ul>
  7. 7. Subject Directories <ul><li>Smaller databases </li></ul><ul><li>Subjects & links meet each other very well </li></ul><ul><li>Organized hierarchically </li></ul><ul><li>Quality over quantity </li></ul><ul><li>Usually maintained by editors (e.g. Yahoo!, BUBL, INFOMINE, LookSmart, dmoz) </li></ul>
  8. 8. Subject Gateways <ul><li>A subject gateway in the context of network-based resource access, can be defined as some facility that allows easier access to network-based resources in a defined subject area. The simplest types of subject gateways are sets of Web pages containing lists of links to resources. </li></ul><ul><li>Subject gateways are also known as subject-based information gateways (SBIGs), subject-based gateways, subject index gateways, virtual libraries, clearing houses, subject trees, pathfinders and other variations thereof. </li></ul><ul><li>Also known as Web portals </li></ul>
  9. 9. Effective Online search strategies <ul><li>Phrase searching </li></ul><ul><li>Truncation </li></ul><ul><li>Wildcard </li></ul><ul><li>Field searching </li></ul><ul><li>Setting Limits </li></ul><ul><li>Boolean </li></ul>
  10. 10. Searching techniques <ul><li>Phrase Searching </li></ul><ul><ul><li>Instead of </li></ul></ul><ul><ul><ul><li>American English </li></ul></ul></ul><ul><ul><li>Try </li></ul></ul><ul><ul><ul><li>“ American English” or ( American English ) </li></ul></ul></ul><ul><li>Truncation </li></ul><ul><ul><li>Instead of </li></ul></ul><ul><ul><ul><li>machine </li></ul></ul></ul><ul><ul><li>Try </li></ul></ul><ul><ul><li>machin ? for machine, machinery, machinist </li></ul></ul>
  11. 11. Searching techniques <ul><ul><li>Instead of </li></ul></ul><ul><ul><ul><li>industry </li></ul></ul></ul><ul><ul><li>Try </li></ul></ul><ul><ul><li> stem </li></ul></ul><ul><ul><ul><li>industr * </li></ul></ul></ul>industr y industr ies industr ial industr ialization
  12. 12. Searching techniques <ul><li>Wildcard Searches </li></ul><ul><ul><li>If you want both </li></ul></ul><ul><ul><ul><li>Wom a n </li></ul></ul></ul><ul><ul><ul><li>Wom e n </li></ul></ul></ul><ul><ul><li>Try </li></ul></ul><ul><ul><ul><li>Wom * n </li></ul></ul></ul><ul><ul><li>If you want to search for </li></ul></ul><ul><ul><ul><li>language literacy acquisition </li></ul></ul></ul><ul><ul><ul><li>language vocabulary acquisition </li></ul></ul></ul><ul><ul><ul><li>language lexical acquisition </li></ul></ul></ul><ul><ul><ul><li>language phonologically acquisition etc. simultaneously; </li></ul></ul></ul><ul><ul><li>Search as </li></ul></ul><ul><ul><ul><li>Language * acquisition </li></ul></ul></ul>
  13. 13. Searching techniques <ul><li>Field Searching </li></ul><ul><ul><li>title, author, subject, keyword, all fields, etc. </li></ul></ul><ul><li>Setting Limits </li></ul><ul><ul><li>language, date, region, file format </li></ul></ul>
  14. 14. Boolean searching “ phonetics” OR “phonology” “ phonetics” AND “phonology” “ phonetics” NOT “phonology”
  15. 15. Searching techniques <ul><li>To find FEWER results, </li></ul><ul><ul><li>Search in specific fields (title, abstract, subject, keywords, etc.) </li></ul></ul><ul><ul><li>Add or change search limits (date, language, etc.) </li></ul></ul><ul><ul><li>Add more search terms (using AND) </li></ul></ul><ul><ul><li>Use phrase searching instead of AND </li></ul></ul><ul><ul><li>Use specific subject headings instead of common language words </li></ul></ul><ul><ul><li>Decrease search terms connected with OR </li></ul></ul>
  16. 16. Searching techniques <ul><li>To find MORE results, </li></ul><ul><ul><li>Use truncation or wildcard characters (* or ?) </li></ul></ul><ul><ul><li>Include more synonyms (using OR) </li></ul></ul><ul><ul><li>Search “all fields” rather than in specific fields </li></ul></ul><ul><ul><li>Remove search limits (e.g. date, language, etc.) </li></ul></ul><ul><ul><li>Use AND instead of phrase searching </li></ul></ul><ul><ul><li>Use broader subject headings </li></ul></ul>
  17. 17. Searching techniques <ul><li>If you received no results at all DON’T WORRY! </li></ul><ul><li>Check speling </li></ul><ul><li>Focus the search to all fields </li></ul><ul><li>Add parenthesis (“ “)to Boolean search </li></ul><ul><li>Check all the wildcards and operators used in search are correct for the database (help files) </li></ul><ul><li>Check the subject headings (whether correct) </li></ul><ul><li>Try other search engine/database </li></ul>
  18. 18. Judging What You Find <ul><li>Accuracy or credibility </li></ul><ul><li>Author or authority </li></ul><ul><li>Coverage or relevance </li></ul><ul><li>Currency </li></ul><ul><li>Objectivity or bias </li></ul><ul><li>Use </li></ul>