Comment on: The measurement of fatigue and chronic fatigue syndrome. [J R Soc Med. 1992]
One thing which hampers medical research is a frustrating tendency for researchers to conclude that heterogeneous groups are homogeneous. Several examples can be cited including research into sudden infant death syndrome. In his editorial on chronic fatigue syndrome (CFS) Wessely (April 1992 JRSM, p 189) asserts that previous views suggesting CFS to be simply a form of somatized depression are no longer tenable because of one published and one unpublished study showing biological differences from major depression. This view is just as untenable as the notion that all CFS is depression. Surely the most likely explanation is that CFS represents a heterogeneous group. The notion that one or two positive findings exclude all other explanations is a dangerous one. Aside from the fact that it negates the possibility of heterogeneity it may have a tendency to narrow thinking on the subject, and this is, after all, the food for medical research.
You can read the full comment here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1293669/pdf/jrsocmed00107-0092a.pdf
Source: Wright B. Chronic fatigue syndrome and heterogeneity. J R Soc Med. 1992 Sep;85(9):588. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1293669/