WillemS said:I think the main problem with phthalate-based blood doping tests is that you have to have two things with such a test: sensitivity and selectivity.
While there is now a considerable amount of evidence that there are testing methods that are highly sensitive to phthalates, the selectivity is somewhat harder. So, if someone transfuses using bags with phthalates, we are pretty sure that we are going to detect it (high sensitivity). At the same time, if we have a positive test, we can't be sure whether the source was really a blood bag or some other source containing phthalates (unknown selectivity).
As I'm not aware of base rates or prior probabilities, any guess towards the probability of blood doping, given Contador's positive plasticizer test, is merely a wild one. For all I know, he could have gotten a positive plasticizer test by sucking to much on a rubber band (plasticizers are used during rubber fabrication) or breathing in too much of that new-car smell (caused by evaporating plasticizers).
yep. positive plasticizer test on a restday prior to the tour's final stages.
just a coincidence
to be sure, it wasn't a wild guess, it was a scientifically supported guess.
or a-big-lot-of-common-sense-guess, if you will.
not a wild guess.