Chapter 4.2, Problem 68E

(a)

To determine

To explain how this experiment used comparison.

Explanation of Solution

In this study, researchers want to study about the day care that help the low income children or not to stay in school and hold good jobs later in life.

Thus, the children were randomly examined over forty years and also half randomly selected children were assigned to an intensive preschool program. Therefore, the given experiment used comparison in the sense of checking the health, IQ level and the test scores of the low income children in the day care. Thus, these were the comparison that were tested for the children before and after they have send to the Day care.

(b)

To determine

To explain the purpose of randomly assigning the babies to the three treatments.

Explanation of Solution

In this study, researchers want to study about the day care that help the low income children or not to stay in school and hold good jobs later in life.

Thus, the children were randomly examined over forty years and also half randomly selected children were assigned to an intensive preschool program.And the purposes of randomly assigning the children were that the low income children whose IQs and health were high and good from the starting does not get a favour so that the results of the research could not be biased. And the results can be accurate.

(c)

To determine

To name two variables that were controlled in this experiment and why it was beneficial to control these variables.

Answer to Problem 68E

Two variables are: the children must be from low-income group and also the children should be in day care.

Explanation of Solution

In this study, researchers want to study about the day care that help the low income children or not to stay in school and hold good jobs later in life.

Thus, the children were randomly examined over forty years and also half randomly selected children were assigned to an intensive preschool program.Therefore, the two variables that are controlled are the children must be from low-income group and also the children should be in day care. It was beneficial to do the same because the low income children can be found easily but the low level income in the day care are not found that easily.

(d)

To determine

To explain how this experiment used replication and what is the purpose of replication in this context.

Explanation of Solution

In this study, researchers want to study about the day care that help the low income children or not to stay in school and hold good jobs later in life.

Thus, the children were randomly examined over forty years and also half randomly selected children were assigned to an intensive preschool program.In this experiment the replication is used. The experiment used replication by giving nutritional supplements and the help from social workers and also the intensive preschool program. The purpose of replication was to check the health of the children and growth of the children such as IQs, test scores, etc. as the time passes.