For example, if the evaluation of a given program does not use any comparison group, the outcomes shown cannot be definitively attributed to the curriculum itself.
The standard answer to the question "Was Irene (or the recent flooding along the Missouri River, or the current record-breaking Texas drought, or [choose your own favorite example]) caused by global warming?" is: No one event can be definitively attributed to climate change (though in some cases, you can get pretty close).
Besides being a ready-made meme, it's usefully imponderable: while peer-reviewed scientific estimates put the annual American death toll of birds from collisions and from outdoor cats at more than three billion, no individual bird death can be definitively attributed to climate change (since local and short-term weather patterns have nonlinear causes).
It is possible he made other translations which have not survived or which cannot be definitively attributed to him.
Although the falling populations can't be definitively attributed to Russia's political instability without stronger evidence, the findings do draw attention to the important connection between social welfare and wildlife health, the authors report online this month in Conservation Biology.
Transmission to 22 HCWs could be definitively attributed to a single patient, with 6 patients transmitting to 1, 1, 2, 5, 6 and 7 HCWs respectively.
No significant adverse reactions have been definitively attributed to the procedure (though there have been two F.M.T.'s that may have led to the transmission of the norovirus stomach bug, both of which cleared on their own within days).
Consequently, the outbreak was definitively attributed to DENV-1 and CHIKV.
