In Exercises 21–28, determine whether the study is an experiment or an observational study, and then identify a major problem with the study.

Medications The Pharmaceutical Research and Manufacturers of America wants information about the consumption of various medications. An independent researcher conducts a survey by mailing 10,000 questionnaires to randomly selected adults in the United States, and she receives 152 responses.

A survey is conducted using 10,000 adults of the United States to gather information about medicine consumption. The total number of responses received is equal to 152.

An observational study is made by noting the answers/responses to a survey. The respondents are not tempered at any level by the surveyor.

An experimental study is made by purposely inculcating changes in the experimental units and then commenting about the behavior observed.

The research comprising 10,000 randomly selected adults and recording their responses to a questionnaire regarding consumption of medications depicts an observational study as the respondents are not affected in any manner.

The small size of the number of responses and convenience-based reporting of answers can lead to incorrect inferences.

Since the number of responses recorded is very small and there can be a bias in reporting the answers as the study is performed on a convenience sample, this study will not lead to accurate outcomes.