…when you are evaluating the effectiveness of full-text searching. Twenty-five years Blair and Maron, An evaluation of retrieval effectiveness for a full-text document-retrieval system, established that size effects the predicted usefulness of full text searching.
Blair and Maron used a then state of the art litigation support database containing 40,000 documents for a total of approximately 350,000 pages. Their results differ significantly from earlier, optimistic reports concerning full-text search retrieval. The earlier reports were based on sets of less than 750 documents.
The lawyers using the system, thought they were obtaining at a minimum, 75% of the relevant documents. The participants were astonished to learn they were recovering only 20% of the relevant documents.
One of the reasons cited by Blair and Maron merits quoting:
The belief in the predictability of words and phrases that may be used to discuss a particular subject is a difficult prejudice to overcome….Stated succinctly, is is impossibly difficult for users to predict the exact word, word combinations, and phrases that are used by all (or most) relevant documents and only (or primarily) by those documents….(emphasis in original, page 295)
That sounds to me like users using different ways to talk about the same subjects.
Topic maps won’t help users to predict the “exact word, word combinations, and phrases.” However, they can be used to record mappings into document collections,that collect up the “exact word, word combinations, and phrases” used in relevant documents.
Topic maps can used like the maps of early explorers that become more precise with each new expedition.