Discovering the modifiers in a terminology data set.

We recently conducted a study of a subset of the data collected in the NLM/AHCPR Large Scale Vocabulary Test (LSVT). We studied those 11,387 terms in the LSVT data that were narrower in meaning than the UMLS concepts mapped to. We hypothesized that when one term is narrower in meaning than another, the first and second terms are likely to differ primarily by modification. We compared three lexical processing methods of increasing sophistication and measured the ability of each of these methods to correctly identify the modifiers in the data set. The results indicate that when using the most powerful of the methods, 63% of the term pairs were found to differ only by premodification, by postmodification or by both, 31% share some lexical material, and the remaining 6% have no lexical items in common. The implications of the study are discussed.