Sunday, January 6, 2008

A level-headed skeptical assessment of echinacaea

It seems that almost everyone either loves or hates echinacaea. Or, at least, there's a vocal core group of people that espouses its miraculous wonders as a cold remedy, and another equally vocal crowd that wants the first to shut up.

At any rate, the research on echinacaea has been mixed and confusing, which is par for the course for an extract of a natural product. just released a commentary on some shoddy reporting of the research, and a resource at the Mayo Clinic shows just how confusing the research has been on echinacaea in particular.

One note about the commentary is worthy of a "lying with statistics" article. Articles from Bloomberg, NTY, and LA Times all reported that prophylactic use echinacaea reduced the rate of getting colds by about 65 percent. However, this number is the reduction in the odds of getting a cold, not a reduction in the probability of getting a cold (about 30 percent). Statistically, the concepts of odds and probability are way different, and the reporting of the odds in this case made echinacaea look way better than the reference study would indicate.

That's not the only issue, but I refer you to the article for more ways of inoculating yourself against questionable reporting of statistics.

One last comment: it doesn't seem the author is against echinacaea or thinks that it is ineffective, but is simply evaluating the quality of the evidence and the reporting of the evidence.