But you didn't ask about the implications of the conclusions, you asked if the methodology was valid, which again I have to say is a question more suited for a science site than a religious one. Or you could do even better by simply contacting the scientists who conducted the study. I believe their contact info is available.
BTW, this isn't "hostility". It's asking a simple question and providing a suggestion that should help you better answer the question you're asking.
EDIT: Turns out it's trivially easy to find the contact info of the main author of the study.
CLICK HERE to see his email address. The paper also describes the methodology you're asking about, which should also help answer your question.