1. A computer-implemented method of providing a response to a query comprising: receiving a query request, to which a response containing a numerical value is expected, from a querying device; identifying at least one input series as relating to the query request, the or each input series containing at least one numerical input measurement corresponding to a potential response to the query request; assigning a weighted score to the or each input series identified as relating to the query request; selecting at least one input series from among the input series identified as relating to the query request, the selection being dependent on the weighted score assigned to the or each input series identified as relating to the query request; generating and providing an individual response to the query request by drawing on a plurality of data sources, wherein each data source is an input series containing at least one numerical input measurement, the response containing a numerical value derived from the or one of the numerical input measurements contained within the selected at least one input series, thereby providing said individual response to the querying device.