Cost-performance analysis of TWX-mediated interlibrary loans in a medium-sized medical center library.

The need for a cost-performance analysis of TWX-mediated versus mail-mediated ILL requests is presented. Three hypotheses are proposed: (1) Unit cost for TWX-mediated ILL requests is greater then for mail-mediated ILL requests; (2) Completion time is shorter for TWX-mediated ILL requests than for mail-mediated ILL requests; (3) An analytic model can be developed that can be used to generate administrative data concerning a TWX installation. The data presented support all three hypotheses. It is shown, also, that through the use of this model a library can arrive at a cost for service of TWX versus mail-mediated ILL.