Homeopathy: the darkling plain

Another small victory for the forces of Unreason. From ‘The Guardian’

Packaging on homeopathic products will be allowed to describe the illnesses they claim to be able to treat under a controversial licensing scheme … but doctors and scientists say it will legitimise products that have no scientific evidence to support their claims

Homeopathic licensing alarms doctors

This is how homeopathic concoctions are prepared. The ‘remedy’ is combined with water in a succession of dilutions and shaken between each dilution, in the case of soluble substances. Originally, each dilution would be in the ratio of 1 part to 100; these days, in the West, dilutions of 1 part in 50,000 is common.

Hahnemann, the inventor of homeopathy, proposed 30 successive dilutions each at 1 part to 100. That is, dilution by a factor of 100³⁰, or 10⁶⁰. To consume a single molecule of a homeopathic remedy at at this 30C solution you’d need to drink about 30,000 litres of water. Chemically, a 30C solution is identical to water.

Homeopaths, undeterred by arithmetic, try to fight their corner. For example, a recent press statement from the Society of Homeopaths objects to Professor Michael Baum’s calling homeopathy an ‘implausible‘ treatment with no convincing evidence of effectiveness:

This is like licensing a witches’ brew as a medicine so long as the bat wings are sterile

Michael Baum, emeritus professor of surgery, University College London

The Society pointed to ‘a large study at the end of 2005, of the outcomes from 6,500 patients at the Bristol Homeopathic Hospital, over a period of six years, in which 75% reported improvement‘.

In fact, this ’study’ at Bristol was no more than a customer satisfaction survey. It did not used a control group, a particularly problemmatic omission as many of the presenting conditions were chronic and/or cyclical and would have shown some improvement anyway. It demonstrated selection bias, as only patients who had elected to receive homeopathic treatment were interviewed. There was no initial assessment of the patients at the start, so the study is subject to recall bias. Patients may be inclined to supply answers the assume the researcher is looking for, introducing another bias. Patients who attended a first appointment but who didn’t return were ignored.

And this is the first study the homeopaths turned to to defend their hokum.

And we are here as on a darkling plain
Swept with confused alarms of struggle and flight,
Where ignorant armies clash by night.

Matthew Arnold, Dover Beach

Links:

• Wikipedia, Homeopathy
• Excluding Bias, Ben Goldacre’s Bad Science
• Society of Witchcraft Homeopaths