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7.4.2  Correspondence with investigators

Review authors will often find that they are unable to extract all of the information they seek from available reports, with regard to both the details of the study and the numerical results. In such circumstances, authors are recommended to contact the original investigators.  Review authors will need to consider whether they will contact study authors with a request that is open-ended, seeks specific pieces of information, includes a data collection form (either uncompleted or partially completed), or seeks data at the level of individual participants. Contact details of study authors, if not available from the study reports, can often be obtained from an alternative recent publication, from university staff listings, or by a general search of the world wide web.