Question

indicate whether the study described as an observational study or controlled experiment.

” people with diabetes are at higher risk for certain cancers in those without the blood sugar diabetes, suggest a new study based on a telephone survey of nearly 400,000 adults.”

Answer 1

Here the subjects (400,000 adults) are not controlled by any external treatment imposed by the observer. In this study it is noted if the people who have/had cancer also have diabetes.

Observational study we measure or survey members of sample without trying to affect them. Here we simply observe and draw conclusion from collected data.

controlled experiment done under controlled condition. That is subjects are chosen and some treatments are applied. Then the affects are noted. Whole experiment is created by experimenter to know the effect of a particular treatment