Chapter 13, Problem 12E

a)

To determine

To find the type of the study.

Answer to Problem 12E

This is an observational study.

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.

This is an observational study because the study used medical records.

b)

To determine

To find whether the study is retrospective or prospective.

Answer to Problem 12E

Retrospective study.

Explanation of Solution

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.

The data collected from medical records. Therefore, it is retrospective study.

c)

To determine

To explain the subjects with their selection.

Answer to Problem 12E

The 981 women who lived near the site of the industrial accident and who were under age 40 at the time.

Explanation of Solution

The subjects are 981 women who lived near the site of the industrial accident and who were under age 40 at the time. The selection method has not been mentioned, but it appears to be a census.

d)

To determine

To find the parameter of interest.

Answer to Problem 12E

The incidence of breast cancer.

Explanation of Solution

In this study, the parameter of interest is incidence of breast cancer.

e)

To determine

To explain the nature and scope of the conclusion.

Explanation of Solution

The selection or assignment is not random as it is observational study. Therefore, there is no way of knowing that dioxin levels cause the increase in breast cancer.