19. A non-transitory computer readable carrier tangibly embodying computer program instructions which, when executed by a computing apparatus, cause the computing apparatus to carry out a method of optimising an automatic information extraction apparatus that extracts data for review by a human curator from digital representations of documents comprising natural language text, the method comprising the steps of: (i) extracting data from at least one digital representation of a document comprising natural language text, using an information extraction module; (ii) providing a computer-user interface which presents the extracted data to a human curator for review and which analyses the interactions between the human curator and the computer-user interface; and (iii) modifying the information extraction module responsive to the analysed interactions to facilitate an improvement in the subsequent performance of a or the human curator using the information extraction module and computer-user interface to review extracted data, the information extraction module being modified so as to change the balance between precision and recall of the information extraction module, whereby a balance that favours precision over recall will lead to fewer incorrect instances of data being extracted than a balance that favours recall over precision, but will omit more data which should have been extracted.
21. A computer readable carrier according to claim 19 , wherein the analysis of the interactions between the human curator and the computer-user interface comprises measuring a metric related to the number of searches made by a curator using a search engine which is operable to find, edit or check extracted data.