Nor would the investigators take time now to write up definitive studies.

We never said it was a definitive study of directors.

Lacking such a definitive study, scientists approach the question in less direct ways.

But after it was under way, other, less definitive studies failed to find any association between dietary fat and breast cancer.

"It's not a definitive study, but it raises concerns with us," she said.

Questions were raised about the fire's long-term health effects, but no definitive studies have established lasting medical damage.

Indeed, many products make it to market well before any definitive studies on their ingredients take place.

At best, he said, such a study gives rise to a hypothesis that can be tested in more definitive studies.

He could have done a 12-pounder, this year's "definitive study," instead of a modest 335 pages.

"If you say prove it, I say the definitive study has not been done."