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

Crime Research A sociologist has created a brief survey to be given to 2000 adults randomly selected from the U.S. population. Here are her first two questions: (1) Have you ever been the victim of a felony crime? (2) Have you ever been convicted of a felony?

A study is conducted based on a survey of 2000 adults. Answers to two of the questions are recorded and analyzed.

Observational study: In this kind of study, inferences are made using the sample without affecting any change in the members of the sample. These studies try to correlate the two effects under consideration without validating the relationship.

Experimental study: In this kind of study, a treatment/factor is allocated to one group of the sample, and the relationship between the two effects under consideration is analyzed. The members of the sample are modified to ease the process of drawing conclusions in the study.

As the answers of the sample of 2000 adults, who are a part of the survey, are observed and recorded without inducing any changes, the study isobservational.

Voluntary responses in a survey result in false conclusions because the respondents’ integrity can be questioned.

Since the respondents’ answers can befalse/biased, so in order to look desirable to the people who are conducting the survey, the results based on this study will not be favourable.