Which of the following are experiments. Circle all that apply. A. A doctor perfo

Question

Which of the following are experiments. Circle all that apply.

A. A doctor performs several diagnostic tests to determine the reason for a patient's illness.

B. A physical therapist tries different procedures to see which one relieves back pain.

C. A clinic gives a drug to a group of ten patients and a placebo to another group of ten patients to find out if the drug has an effect on the patients' illness.

D. A stock analyst selects a stock from a group of twenty for investment by choosing the stock with the greatest earnings per share reported for the last quarter.

Explanation / Answer

The basic difference between an experiment and an observational study is that in an experiment treatments are applied to experimental units and then their effect is observed whereas in observational study variables are measured to determine the effect of one variable on another but no treatment is applied.

In the first option, the doctor is just observing and performing tests to determine the reason of illness and hence it is a observational study.

In the second option, different treament methods are applied and their effect is measured and hence it is an experimetal study.

In the third option, the effect of drug (which is a treatment in this case) is tested and hence it is also an example of experimental study.

In the fourth option, only an observation is being made and hence it is an example of observational study.

Therefore the correct options are :

B. A physical therapist tries different procedures to see which one relieves back pain.

C. A clinic gives a drug to a group of ten patients and a placebo to another group of ten patients to find out if the drug has an effect on the patients' illness.

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