%0 Journal Article %T Systematic reviews, systematic error and the acquisition of clinical knowledge %A Steffen Mickenautsch %J BMC Medical Research Methodology %D 2010 %I BioMed Central %R 10.1186/1471-2288-10-53 %X The various types of clinical knowledge sources are categorised on the basis of Kant's categories of knowledge acquisition, as being either 'analytic' or 'synthetic'. It is shown that these categories do not act in opposition but rather, depend upon each other. The unity of analysis and synthesis in knowledge acquisition is demonstrated during the process of systematic reviewing of clinical trials. Systematic reviews constitute comprehensive synthesis of clinical knowledge but depend upon plausible, analytical hypothesis development for the trials reviewed. The dangers of systematic error regarding the internal validity of acquired knowledge are highlighted on the basis of empirical evidence. It has been shown that the systematic review process reduces systematic error, thus ensuring high internal validity. It is argued that this process does not exclude other types of knowledge sources. Instead, amongst these other types it functions as an integrated element during the acquisition of clinical knowledge.The acquisition of clinical knowledge is based on interaction between analysis and synthesis. Systematic reviews provide the highest form of synthetic knowledge acquisition in terms of achieving internal validity of results. In that capacity it informs the analytic knowledge of the clinician but does not replace it.Systematic reviews, in healthcare, have been described as providing objective overviews of all the evidence currently available on a particular topic of interest [1]. Such overviews cover clinical trials in order to establish where effects of healthcare are consistent and where they may vary. This is achieved through the use of explicit, systematic methods aimed at limiting systematic error (bias) and reducing the chance of effect [2]. Systematic reviews have been recommended as providing the best source of evidence to guide clinical decisions [3,4] and healthcare policy [5], and they receive twice as many citations as non-systematic reviews in peer-review %U http://www.biomedcentral.com/1471-2288/10/53