Lack of control group David Corney, University College London 17 April 2009 There appears to be no control group in the analysis described, making it hard to come to any conclusion about the effectiveness or otherwise of the homeopathic treatments. The patients report that their symptoms improve over time, but how does this compare with either a) no treatment; or b) 'conventional' medical treatment? This seems especially important for a diagnosis such as "headache", if the follow-up is 2 or 8 years later. Surely most headaches have cleared up by then anyway? Competing interests I have no competing interests.