Types of study in medical research: part 3 of a series on evaluation of scientific publications.
BACKGROUND
The choice of study type is an important aspect of the design of medical studies. The study design and consequent study type are major determinants of a study's scientific quality and clinical value.


METHODS
This article describes the structured classification of studies into two types, primary and secondary, as well as a further subclassification of studies of primary type. This is done on the basis of a selective literature search concerning study types in medical research, in addition to the authors' own experience.


RESULTS
Three main areas of medical research can be distinguished by study type: basic (experimental), clinical, and epidemiological research. Furthermore, clinical and epidemiological studies can be further subclassified as either interventional or noninterventional.


CONCLUSIONS
The study type that can best answer the particular research question at hand must be determined not only on a purely scientific basis, but also in view of the available financial resources, staffing, and practical feasibility (organization, medical prerequisites, number of patients, etc.).
Röhrig
Bernd
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MDK Rheinland-Pfalz Referat Rehabilitation/Biometrie Albiger Str. 19 d 55232 Alzey, Germany. bernd.roehrig@mdk-rlp.de
du Prel
Jean-Baptist
JB
Wachtlin
Daniel
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Blettner
Maria
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D035843:Biomedical Research; D002986:Clinical Trials as Topic; D005858:Germany; D010506:Periodicals as Topic; D012106:Research; D012586:Science