1. A method of ranking a document cluster which includes one or more documents, the method comprising: obtaining, at a document cluster ranking system, a value associated with a first feature for each of a plurality of document clusters; based on the values associated with the first feature, automatically generating, at the document cluster ranking system, a plurality of first feature bins, each first feature bin defining a range of values and a bin identifier; and obtaining a score for one of the document clusters, by: identifying the first feature bin having a range of values which includes the obtained value associated with the first feature for that one of the document clusters; and determining a score for that document cluster based on the first feature bin identifier for the identified first feature bin.