1. A method for indexing a plurality of documents, each document comprising a text portion, the method comprising: a) parsing the text portion of each of the plurality of documents to form a plurality of respective local document indexes each associated with a respective document, and storing the local document index in a database, wherein each local document index comprises a plurality of local text terms contained in the respective document and a local weighting associated with each text term; b) from the plurality of local document indexes, forming a global document index comprising a plurality of global text terms contained in the plurality of documents, and a global weighting associated with each global text term; wherein the global weighting associated with each of the global text terms is determined with respect to a parameter associated with a reference global text term.