Chapter 13, Problem 34E

To determine

To explain whether an observational study or an experimental study is appropriate and create a design.

Explanation of Solution

First need to understand about the experimental study and observational study:

Experimental study: Assigning people or things to groups and applying some treatment to one group, while the other group does not receive the treatment.

Observation study: In an observational study, measure or survey members of a sample without trying to affect them.

There are two types of Observational study:

Retrospective: The data are collected from the past by going back in time.

Prospective: The data are collected in the future.

Therefore, use of a retrospective observational study since there is no way you can manipulate the phases of the moon. We need to collect data randomly of police and emergency room logs from the past 3 years. From the data we need to analyze the number of cases for the days where there is a full moon, where is a waxing moon, a waning moon, and when the moon is nearly dark. From analysis, need to compare the groups. Therefore, here observational study would be useful.