[specialist]

If you decide to ignore those in your study because you want to study something specific then you should make it very, very clear.

I don't know how cavalle could be more clear:

s/he's not judging the study design, but rather the popular report of the study results.

[fnordfnordfnord]

Is the newspaper report non-factual? It even mentions the researcher's caveat not to use cocaine during pregnancy.

"Hurt, who is also a professor of pediatrics at the University of Pennsylvania, is always quick to point out that cocaine can have devastating effects on pregnancy."