A method used by researchers to try to bring together related published (and sometimes unpublished) studies dealing with similar treatments or similar disorders. The process starts with trials (see RANDOMISED CONTROLLED TRIAL) as the basis of collecting information. A search of the medical literature will reveal all such related trials which can then be analysed and combined in a systematic review. In this way, it is possible to try to obtain more accurate results than might be possible in a single trial, especially if it involved only a small number of patients. Such reviews can then be re-evaluated and re-analysed to deal with such problems as biased initial recruitment or faulty statistical analysis, in an attempt to refine the results. This procedure is described as meta-analysis. The technique is used increasingly in medicine, with the COCHRANE COLLABORATION in the forefront of systematically reviewing and storing clinical and research data to provide a reliable information base on which to take forward the practice of EVIDENCE-BASED MEDICINE.