The difference between an observational study and an experiment is that...
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in an observational study, the researchers do not control treatment, and in an experiment, they do.

in an experiment, one group is studied over a short period of time, and in an observational study, the group is studied over a longer period of time.

in an experiment, cause-and-effect is analyzed, and in an observational study, it is not.

in an observational study, only one group is studied, and in an experiment, two groups are studied.

A company wants to collect opinions on employee working conditions. Which group of individuals would be the best choice for a random sample?

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The names of 25 employees that have taken 5 or more sick days in the last quarter are chosen out of a hat and asked their opinion about the working conditions.

The names of 25 employees are chosen out of a hat and asked their opinion about the working conditions.

The names of 25 employees that have volunteered to take a survey are asked their opinion about the working conditions.

The first 25 employees that clock in on a Monday morning are chosen out of a hat and asked their opinion about the working conditions.

Pollsters take a survey of people at a ball game to collect and analyze data about favorite leisure activities of Star City’s residents. Would this study be biased? Why or why not?

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No, it is not biased. The sample of people at the ball park is representative of Star City’s residents.

No, it is not biased. All people at the ball park will respond to the survey.

Yes, it is biased. The sample of people at the ball park is not representative of Star City’s residents.

Yes, it is biased. Not all people at the ball park will respond to the survey.