9. A tangibly embodied non-transitory computer-readable storage medium storing instructions, that, when executed by a processor, perform a ranking method comprising: sending, to a remote computer system via a network, a search query containing query terms; obtaining, at the remote computer system, documents resulting from performing the search query on a document database, the documents containing such terms that match the search query; determining base relevancy scores for the documents; adjusting the base relevancy scores by applying a lead boosting value calculated according to an influence function, the influence function promoting a particular word position in a document, the particular word position being a predetermined number of words from the beginning of the document; and ranking the documents according to the adjusted base relevancy scores.
9. A tangibly embodied non-transitory computer-readable storage medium storing instructions, that, when executed by a processor, perform a ranking method comprising: sending, to a remote computer system via a network, a search query containing query terms; obtaining, at the remote computer system, documents resulting from performing the search query on a document database, the documents containing such terms that match the search query; determining base relevancy scores for the documents; adjusting the base relevancy scores by applying a lead boosting value calculated according to an influence function, the influence function promoting a particular word position in a document, the particular word position being a predetermined number of words from the beginning of the document; and ranking the documents according to the adjusted base relevancy scores. 10. The tangibly embodied non-transitory computer-readable storage medium of claim 9 , the method further comprising: adjusting the base relevancy scores based on measuring relative distances between the terms that match the search query in the documents according to a probability distribution function.