Development of methodologic tools for planning and managing library services. II. Measuring a library's capability for providing documents.

A method of measuring a library's capability for providing the documents its users need has been developed. The library is tested with a representative sample of such documents to determine how long would be required for users to obtain these documents. Test results are expressed in terms of a Capability Index, which has a maximal value of 100 only if all the sample documents are found "on shelf." Specific tests employing samples of 300 documents have been developed that are appropriate for academic and for "reservoir" biomedical libraries. Realistic field trials have demonstrated that these two tests are practical to administer and that test results are adequately reproducible. When strict comparability is not important, a library can test itself. In assessing a reservoir library, test results are supplemented by data on its typical processing time for interlibrary loan requests. Currently these tests are being used in a national survey. The general method is applicable to other types of libraries, provided appropriate test samples are established. If their limitations are clearly understood, these "Document Delivery Tests" can be valuable tools for planning and managing library services.