The CT scan can improve the reliability of assessment of pelvic stability because of its ability to identify anatomical features of injury. The Young-Burgess system may be optimal for the learning surgeon. The Tile classification system is more beneficial for specialists in pelvic and acetabular surgery.

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Abstracts (and other short surrogates for the complete text) of a document have been generally considered a valuable aid to the reader in quickly determining the relevance of a document (as well as, in some cases, serving as a substitute for reading the text, and as a separate surrogate in secondary services). A test of this hypothesis was conducted in the form of a field experiment in three military laboratories. Based on what a sample of 85 scientists and engineers reported on the time they took and the relevance judgments they made with respect to the documents which came across their desks over a four week period, there does not appear to be any evidence to support the assumption that abstracts, accompanying a document, have any significant effect.

This paper describes a particular strategy and method of field testing or evaluation: administrative experimentation. The method is first defined in terms of its relation t o other methods, and its potential strengths and limitations. Second, the method itself is described in some detail. Finally, case studies of its use are presented to provide a basis for evaluating the usefulness of the method.