16. Apparatus for numeric information retrieval, comprising: electronic memory storing a computer-searchable index, the index comprising a plurality of searchable index entries, at least a plurality of the entries each including a representation of an associated unit of measure extracted from the electronic source documents; a computer system, being programmed to receive a query, said query comprising one or more keywords; said computer system being further programmed to automatically generate a query unit, at least partly by determining a correlation within the electronic source documents between the keywords and one or more of the units included in the index, wherein determining the correlation includes scoring how closely related each of said one or more keywords and one or more of said units appear to be within the electronic source documents; and said computer system being further programmed to assess the relevance of one or more of the index entries to the query, based at least partly on a comparison of the query unit and the unit associated with each of said index entries.
16. Apparatus for numeric information retrieval, comprising: electronic memory storing a computer-searchable index, the index comprising a plurality of searchable index entries, at least a plurality of the entries each including a representation of an associated unit of measure extracted from the electronic source documents; a computer system, being programmed to receive a query, said query comprising one or more keywords; said computer system being further programmed to automatically generate a query unit, at least partly by determining a correlation within the electronic source documents between the keywords and one or more of the units included in the index, wherein determining the correlation includes scoring how closely related each of said one or more keywords and one or more of said units appear to be within the electronic source documents; and said computer system being further programmed to assess the relevance of one or more of the index entries to the query, based at least partly on a comparison of the query unit and the unit associated with each of said index entries. 21. The apparatus of claim 16 , wherein each of the index entries represents an item of numerical data comprising a unit of measure and a numerical value, said items of numerical data extracted from the electronic source documents.