2 research outputs found
The extension and application of Swet's theory of information retrieval
Phd ThesisThe thesis comprises (1) 8 critical interpretation of Swets's
contribution to information retrieval, (2) development (i.e.
"extension") of the formalism, as so interpreted, and (3) a
description of an experiment that identifies hypotheses consistent
with the extended formalism. The early sections of the thesis
place the original contribution by Swets in the contexts of both
signal-detection theory and information retrieval theory. It is
then argued that as the original theoretical contribution is
ambiguous in key respects, an interpretation of it is necessary.
The interpretation given constitutes an initial development of
Swets's work but other developments, not simply a consequence of
the interpretation of the original description by Swets, are also
put forward. The major one of these is the explicit incorporation
in the formalism of logical search expressions. Elementary logical
conjuncts of search terms are seen as (1) being weakly ordered by
"document ordering expressions", and (2) having probability-pairs
attached to disjunctions of them defined by the ordering. A major
part of the thesis is the identification of novel hypotheses,
expressed within the extension of the original formalism, which
relate to triples of: (1) instances of information need in medicine,
represented by prespecified partitionings of a medical-literature
data base (MEDLARS), (2) an analytical document ordering expression,
and (3) an algorithmically-derived set of terms characterising the
information need. An enhancement is suggested to data base management
programs that at present employ only user-specified logical
search expressions by way of search input, this enhancement
stemming directly from the extension of the original formalism. The
broad conclusion of the thesis is that when the original contribution
of Swets is suitably interpreted and extended, a robust, hospitable
conceptual framework for describing information retrieval at the
macroscopic level is provided