The study doesn't prove cause and effect.

There is, of course, no way to prove the cause and effect here.

These so-called epidemiological studies can never prove cause and effect.

"It is difficult to prove cause and effect on the ground where multiple factors interact in complex ways," she said.

Still, the study doesn't prove cause and effect.

The study did not prove cause and effect, they said.

But all this observation can do is find associations: it can't prove cause and effect.

Observational studies such as this one don't prove cause and effect.

Studies such as these can only indicate a statistical association, not prove cause and effect.

A spokeswoman for the meat industry, however, said the study did not prove cause and effect.