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Chapter 4: Problem 64

Does day care help low-income children stay in school and hold good jobs later in life? The Carolina Abecedarian Project (the name suggests the \(\mathrm{ABC}\) s) has followed a group of 111 children since 1972. Back then, these individuals were all healthy but low-income black infants in Chapel Hill, North Carolina. All the infants received nutritional supplements and help from social workers. Half were also assigned at random to an intensive preschool program. \({ }^{36}\) Explain how each of the four principles of experimental design was used in this study.

Short Answer

Expert verified
The study used randomization, control groups, replication, and control of confounding variables effectively.

Step by step solution

01

Identify the Purpose

The purpose of the study is to examine the long-term effects of an intensive preschool program on low-income children, specifically on their educational and employment outcomes later in life.
02

Outline the Randomization Process

Randomization was used to assign half of the 111 children to the intensive preschool program. This ensures that the assignment to the intervention or control group is not biased and helps to eliminate confounding variables, making the results more reliable.
03

Explain the Control Group

A control group was established comprising the children who did not receive the intensive preschool program, but still received nutritional supplements and help from social workers. This provides a baseline to compare the outcomes of those who attended preschool.
04

Define the Replication Aspect

Although the study involves only one cohort of children, the principle of replication is reflected in the follow-up over several years to observe long-term outcomes. This allows for repeated observation of effects and strengthens the findings if similar patterns emerge over time.
05

Ensure Control of Confounding Variables

Confounding was controlled not only through randomization but also by ensuring that all children involved in the study received nutritional supplements and social worker assistance, thus isolating the effect of the preschool program itself as the variable being tested.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Randomization
Randomization is a crucial element in experimental design to ensure fairness and reliability. In the Carolina Abecedarian Project, randomization was used to assign the children to either the intensive preschool program or the control group. This process helps in ensuring that there is no bias in assigning participants to different groups. By doing this, the researchers aimed to make sure that each group was similar at the start of the experiment.
  • Randomization prevents bias in assignment.
  • It helps in balancing out unknown factors that could affect the study鈥檚 outcome.
By eliminating such biases, the study's results reflect the true impact of the preschool program on the children's later life outcomes.
Control Group
Having a control group is essential in experimental studies for creating a baseline for comparison. In this study, the control group consisted of children who did not receive the intensive preschool program but still got nutritional supplements and social worker support. This setup allows researchers to see the effects of the preschool program more clearly because they can compare it against a group that received similar other conditions.
  • The control group provides necessary contrast to measure program impact.
  • It helps differentiate the results attributed to the preschool program rather than other received benefits.
This comparison helps to identify what changes, if any, can be directly attributed to the preschool education.
Confounding Variables
Confounding variables can muddy the results of an experiment by mixing the effects of the variable being studied with other unrelated factors. In this project, efforts were made to control confounding variables by providing all participants with the same baseline benefits, such as nutritional supplements and social worker assistance, regardless of their group. This way, the effect of the preschool program itself could be isolated and studied independently.
  • Uniform baseline conditions help control confounding effects.
  • Ensures the differences in outcomes are due to the intervention itself.
By considering potential confounding factors, researchers could focus their analysis on the impacts attributable to the preschool intervention.
Replication
Replication involves conducting an experiment multiple times to verify the results. While the Carolina Abecedarian Project tracked only one cohort, its design included long-term follow-up over several years. This process allows researchers to observe the lasting effects of the preschool program on various life aspects like education and employment.
  • Long-term tracking acts as a form of replication.
  • Observing consistent patterns strengthens the validity of findings.
By following participants over decades, the study could assess the sustained influence of early education, reinforcing the credibility of its observations.

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Most popular questions from this chapter

In which of the circumstances below would you allow collecting personal information without the subjects' consent? (a) A government agency takes a random sample of income tax returns to obtain information on the average income of people in different occupations. Only the incomes and occupations are recorded from the returns, not the names. (b) A social psychologist attends public meetings of a religious group to study the behavior pattems of members. (c) A social psychologist pretends to be converted to membership in a religious group and attends private meetings to study the behavior patterns of members.

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Nurse-practitioners are nurses with advanced qualifications who often act much like primary-care physicians. Are they as effective as doctors at treating patients with chronic conditions? An experiment was conducted with 1316 patients who had been diagnosed with asthma, diabetes, or high blood pressure. Within each condition, patients were randomly assigned to either a doctor or a nurse-practitioner. The response variables included measures of the patients' health and of their satisfaction with their medical care after 6 months. \(^{44}\) (a) Which are the blocks in this experiment: the different diagnoses (asthma, and so on) or the type of care (nurse or doctor)? Why? (b) Explain why a randomized block design is preferable to a completely randomized design here.
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