Determine whether the description corresponds to an observational study or an experiment. research is conducted to determine if there is a relation between lung capacity and proximity to coal mines. nothing nothing does the description correspond to an observational study or an experiment?

The description corresponds to an observational study.

Explanation:

In Observational studies, researchers observe the effect of a risk factor without changing what is exposed to it or its conditions. On the other hand, in an experimental study, researchers can introduce a change and study the effects of it.

answer:

d. because dr. laguardia selected a widely used measure, his study generalizes to has strong external validity. external validity has limited external validity. other applications of this measure.

the widely used measure that he applied to his experiment was the benton facial recognition test. it employed on to football players and as result, only players who suffered brain concussions did not pas this test. and although it has an external validity, it is limited because it isn't general to apply to other population.

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