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Data Extractors

Explore study, variable, and case selection methods, retrieval techniques, and simple analysis capabilities in data extraction. Learn the best practices for modular and standard-based systems that are portable and off-the-shelf.

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Data Extractors

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Presentation Transcript

  1. Data Extractors • Summary of Features • Delivery Strategies • Best Practices

  2. Summary of Features • Study selection methods • Variable selection methods • Case selection methods • Methods of downloading or retrieving subsets • Simple analysis capabilities

  3. Study Selection Methods • simple an extractor for a single study • list of study titles or titles organized by subject headings • a searchable catalogue of titles or variables within studies

  4. Variable Selection Methods • list of variable names • a subject index linked to a list of variables Either may include the data dictionary entry for individual variables.

  5. Case Selection Methods • a set of pre-selected demographic variables • declare through Boolean expressions using variables within a study • through a random selection of cases

  6. Methods of Retrieval • use of an ftp site, anonymous or logon • download from a Web page

  7. Simple Analysis Capabilities • frequency distributions or descriptive statistics for individual variables • simple tables of two-way tabulations or descriptive summaries • simple charts or graphs

  8. Delivery Strategies • full client application • a helper application or plug-in • CGI and database applications • a network programming application

  9. Delivery Strategies • full client application • independent program written to communicate with a specific server • advantage: the client has complete communication control with the server • disadvantage: the development costs to program and support a full client

  10. Delivery Strategies • a helper application or plug-in • an application operating in conjunction with a Web browser • advantage: the Web browser handles the network communication • disadvantage: the development costs to program and support the application

  11. Delivery Strategies • CGI and database applications • the use of Web forms to drive database requests • advantage: the Web browser handles the network communication and supports multiple platforms • disadvantage: feeding and caring the database needs standard products

  12. Delivery Strategies • a network programming application • network-programs operating with a Web browser • advantage: the same Web advantages as before plus added functionality • disadvantage: same database concerns as before plus the costs of programming

  13. Best Practices • modularity • based on standards • easy to migrate • portable • off-the-shelf

  14. Best Practices • modularity • a system of single-tasked utilities that communicate easily among themselves

  15. Best Practices • based on standards • accepted practices for organizing and building systems • the communication among modules depends on standards

  16. Best Practices • easy to migrate • easily adapt with changes in new technology • primarily, the data documentation and data must outlive current software and hardware

  17. Best Practices • portable • easily used with a variety of systems, including MS/Windows, Unix and MacOS

  18. Best Practices • off-the-shelf • acquire components that are commercially produced

  19. Directions to Take • CARL CFI proposal • phone conference Tuesday, Nov 30 • Future Directions for DLI • moving from a pilot project to a permanent program • Strategies for COPPUL

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