Advanced Search Techniques using Natural Language Processing
by Tony Rose,
FreePint Newsletter 172
"Most readers will, no doubt, be familiar with Google and other
Internet search engines: type in a few key words to describe your
information need, hit return and within a second or two you are
presented with a list of links to documents that you hope will be
relevant to your query. Evidently, a proportion of them will indeed be
relevant (we refer to this measure as the 'precision' of the search
engine) and, if you are lucky, you may also find that all the known
relevant documents will be in the list somewhere (we call this measure
'recall'). Of course, on the web we can never really calculate a true
recall figure, as there is simply no way of ever knowing just how many
relevant documents there are out there. But for a fixed collection
such as a library or corporate database, the recall figure can be a
very important measure of a retrieval system's effectiveness."