Transcript Unit B PPT
Internet Research – Illustrated, Fourth Edition Unit B Internet Research: Unit B Constructing Complex Searches Internet Research – Illustrated, Fourth Edition 2 Objectives Understand Boolean operators Narrow a search with the AND operator Expand a search with the OR operator Restrict a search with the AND NOT operator Internet Research – Illustrated, Fourth Edition 3 Objectives (cont) Use multiple Boolean operators Search with filters Combine Boolean operators & filters Use metasearch engines Internet Research – Illustrated, Fourth Edition 4 Constructing Complex Searches Complex searches ~ searches using Boolean operators to expand, narrow, and restrict search results ~ also called advanced searches Internet Research – Illustrated, Fourth Edition 5 Understanding Boolean Operators Boolean operators are special words or symbols used to connect keywords and phrases in a search Boolean operators: ▪ AND / + ▪ OR ▪ AND NOT / - Internet Research – Illustrated, Fourth Edition 6 TERMS TO USE Boolean operators ~ words & symbols that connect keywords & phrases to tell search tools how to interpret a search Default operator ~ the Boolean operator used automatically by a search tool (most search tools use AND) Internet Research – Illustrated, Fourth Edition 7 CLUES TO USE Always use all CAPITAL LETTERS for Boolean operators Internet Research – Illustrated, Fourth Edition 8 Understanding Boolean Operators ~ define the relationships between keywords and phrases and help focus search results ~ either narrow or broaden a search, thereby decreasing or increasing the number of results ~ are based on Boolean logic, a mathematical syntax, in which keywords act as nouns and the operators act as conjunctions, joining keywords in a way that search tools can interpret Internet Research – Illustrated, Fourth Edition 9 Venn Diagrams Venn diagrams ~ are used to illustrate Boolean logic and searches using Boolean operators ~ were created by John Venn to explain visually what George Boole, creator of Boolean Algebra, had described symbolically: the intersection, union, and exclusion of sets Internet Research – Illustrated, Fourth Edition 10 Venn Diagrams Each circle represents a set or Web pages returned by one concept in a search. When circles overlap it indicates some pages are returned for both concepts. The area of overlap is the intersection of the sets. When a search returns all of the pages in both circles, it is the union of the sets. When a set is left out of results, it is an exclusion of the set. Internet Research – Illustrated, Fourth Edition 11 Venn Diagrams Using Venn diagrams to represent Boolean searching: This represents the results for a search. Every Web page that contains the search terms is in this set. one set Internet Research – Illustrated, Fourth Edition 12 Venn Diagrams Using Venn diagrams to represent Boolean searching: This represents a search using AND to limit the results. intersection of two sets Every Web page that contains both search terms is in the highlighted intersection of the two sets. Internet Research – Illustrated, Fourth Edition 13 Venn Diagrams Using Venn diagrams to represent Boolean searching: This represents a search using OR to expand the results. union of two sets Every Web page that contains either search term is in the highlighted union of the two sets. Internet Research – Illustrated, Fourth Edition 14 Venn Diagrams Using Venn diagrams to represent Boolean searching: This represents a search using AND NOT to limit the results. Every Web page that contains the search term in the white set is excluded from the results, which are highlighted in green. exclusion of a set Only pages containing the first search term (in green), but not containing the second search term (in white), are included in results. Internet Research – Illustrated, Fourth Edition 15 CLUES TO USE When uncertain about which Boolean operator to use in a search, sketch a quick Venn diagram and label it with your search terms and it will become clear. Internet Research – Illustrated, Fourth Edition 16 TERMS TO USE Syntax ~ rules in a language, like grammar, that standardize usage Venn diagrams ~ drawings used to represent Boolean logic and searches using Boolean operators Internet Research – Illustrated, Fourth Edition 17 Narrowing the Search with the AND Operator The AND operator ~ AND narrows or limits your search, thereby decreasing the number of search results Internet Research – Illustrated, Fourth Edition 18 Narrowing the Search with the AND Operator Use AND to: ▪ focus or narrow your results ▪ force the search of a stop word Internet Research – Illustrated, Fourth Edition 19 Narrowing the Search with the AND Operator An intersection of two sets occurs when you use AND: apples plums Web pages containing apples Web pages containing plums Web pages containing both apples and plums. Internet Research – Illustrated, Fourth Edition 20 CLUES TO USE Most search engines accept + instead of AND Some search engines require using + instead of AND Always leave a space in front of + Never leave a space after + Internet Research – Illustrated, Fourth Edition 21 Expanding the Search with the OR Operator The OR operator ~ OR expands or broadens your search, thereby increasing the number of search results Internet Research – Illustrated, Fourth Edition 22 Expanding the Search with the OR Operator Use OR to: ▪ to broaden or expand your results ▪ to combine synonyms and related words ▪ to have two spellings of a word returned (for example: draught or draft) Internet Research – Illustrated, Fourth Edition 23 Expanding the Search with the OR Operator A union of two sets occurs when you use OR: apples plums Web pages containing either apples or plums. Internet Research – Illustrated, Fourth Edition 24 Restricting Queries with the AND NOT Operator The AND NOT Operator ~ AND NOT limits or narrows your search by excluding or restricting a concept from your results, thereby decreasing the number of results Internet Research – Illustrated, Fourth Edition 25 Restricting Queries with the AND NOT Operator Use AND NOT when: ▪ finding too many irrelevant results ▪ excluding a concept from your results Internet Research – Illustrated, Fourth Edition 26 Restricting Queries with the AND NOT Operator Using AND NOT excludes a concept: apples Web pages containing apples but not plums. plums Web pages where the sets intersect are excluded, even though they contain apples, because the results must exclude any page containing plums. So, you are left with pages that contain apples without containing plums. Internet Research – Illustrated, Fourth Edition 27 CLUES TO USE Most search engines accept instead of AND NOT Some search engines require using instead of AND NOT Always leave a space in front of Never leave a space after - Internet Research – Illustrated, Fourth Edition 28 Using Multiple Boolean Operators Using multiple Boolean operators ~ provides more focused, relevant results Internet Research – Illustrated, Fourth Edition 29 CLUES TO USE When using multiple Boolean operators, use parentheses ( ) to separate concepts and to force the order in which your search is performed. Internet Research – Illustrated, Fourth Edition 30 TERMS TO USE Forcing the order of operation ~ using parentheses in a complex query to force the search tool to perform the part of the search inside the parentheses Internet Research – Illustrated, Fourth Edition 31 Searching with filters Searching with filters ~ narrows your search by telling search tools to screen out specified types of Web pages ~ returns fewer results that are more relevant Internet Research – Illustrated, Fourth Edition 32 Searching with filters Language filter ~ limits search to language you choose File format filter ~ limits search to file format you choose Date filter ~ limits search to pages first seen (or sometimes last updated) within a specified time period Internet Research – Illustrated, Fourth Edition 33 Searching with filters Location filter ~ limits search to pages containing your keywords in the location you choose Domain filter ~ limits search to a specified domain Censoring filter ~ limits search by attempting to filter potentially offensive pages Internet Research – Illustrated, Fourth Edition 34 Combining Boolean Operators and Filters Use both Boolean operators & filters ~ when you need to perform very specific searches to return the most relevant results Internet Research – Illustrated, Fourth Edition 35 Using Metasearch Engines Use metasearch engines ~ when you need to see the most highly ranked results from multiple search engines ~ to identify which search engine might be best for a specific search Internet Research – Illustrated, Fourth Edition 36 Using Metasearch Engines Metasearch engines: – – – – – – dogpile Fazzle ixquick metaCrawler Search.com Vivisimo Internet Research – Illustrated, Fourth Edition 37 CLUES TO USE Since metasearch engine results can be inconsistent, verify an engine you want searched was actually used for your search If you don’t know that the metasearch engine you are using can translate your query effectively, use simple searches Internet Research – Illustrated, Fourth Edition 38 Constructing complex searches includes: understanding Boolean operators using AND to narrow a search using OR to expand a search using AND NOT to restrict a search understanding filters using filters with Boolean operators using metasearch engines Internet Research – Illustrated, Fourth Edition 39 INTERNET RESEARCH End