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DLI Training Workshop

Hosted by

Dalhousie UniversityMarch 2000

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Data Extractors

Summary of FeaturesDelivery StrategiesBest Practices

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Summary of Features

Study selection methods Variable selection methods Case selection methods Methods of downloading or

retrieving subsets Simple analysis capabilities

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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

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Variable Selection Methods

list of variable namesa subject index linked to a list of variables

Either may include the data dictionary entry for individual variables.

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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

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Methods of Retrieval

use of an ftp site, anonymous or logon

download from a Web page

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Simple Analysis Capabilities

frequency distributions or descriptive statistics for individual variables

simple tables of two-way tabulations or descriptive summaries

simple charts or graphs

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Delivery Strategies

full client application a helper application or plug-in CGI and database applications a network programming application

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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

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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

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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

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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

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Best Practices

modularity based on standards easy to migrate portable off-the-shelf

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Best Practices

modularity a system of single-tasked utilities

that communicate easily among themselves

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Best Practices

based on standards accepted practices for organizing

and building systems the communication among

modules depends on standards

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Best Practices

easy to migrate easily adapt with changes in new

technology primarily, the data documentation

and data must outlive current software and hardware

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Best Practices

portable easily used with a variety of

systems, including MS/Windows, Unix and MacOS

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Best Practices

off-the-shelf acquire components that are

commercially produced

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Directions to Take

CARL CFI proposal NILDS

Future Directions for DLI moving from a pilot project to a

permanent program Strategies for future collaboration