To his surprise, Hein Lodewijkx, a Dutch statistician and psychologist, discovered that never a statistical study was conducted on the correlation between doping and the average velocity in big cycling tours. He was not less surprised by his observation that studies on which the conclusions of anti-doping agencies are based, are not at all representative for the professional sporter. In 2008, two double blind experiments were conducted, but on recreative sporters only. 'Double blind' means that subjects and researchers have no information on treatments. His hypothesis was that if epo influences the performance of a professional sporter, this should be seen when analyzing historical data, e.g. by comparing data before and after epo was introduced in the peleton in 1990. So, he compared the average velocities of the three largest cycling tours (France, Italy and Spain) in the period from 1903 until now. Moreover he compared the velocities of the montain stages and time trials. Guess what! No significant difference was found!. Eighty nine percent of the differences was explained by non-doping related factors such as the length and the altitude of the stages. This of course is an interesting observation that in my vieuw leads to the conclusions that (1) the effect of doping (here epo) is completely masked by other non-controllable factors and (2) that the usage of doping does not falsify the result of a contest.
Remains the question why sportifs (and their assistants) believe in the effect of epo and other forms of (blood) doping. Or, does epo provide a psychological advantage, the feeling of a winner? The effect of such psychological factors is the subject of a 4-years study conducted by the team of Hein Lodewijkx. Unfortunately, I very much fear that Alberto Contador's fate will be sealed long before this psychological study may prove his innocence.
Source: Edo Sturm, Interview with Hein Lodewijkx, "Effect doping wordt vaak schromelijk overdreven", Trouw, 11 november 2010