A health psychologist wants to determine whether children who eat breakfast perf

Question

A health psychologist wants to determine whether children who eat breakfast perform better on school work than children who do not have a breakfast meal. She gathers two groups for her comparison, 15 children who have a normal breakfast meal and another 15 who do not have breakfast, on a day when they have a math test scheduled in the mid-morning at school. The psychologist plans to use scores on the math test as an indicator of school performance. Respond to the prompts below.

- What statistical test would be appropriate in this case? Explain the rationale for your answer.

- Identify the independent variable in this study.

- Identify the dependent variable in this study.

- Describe a potentially confounding variable and explain how that might affect the conclusions from the study.

- State the null and alternative hypotheses in words.

Explanation / Answer

Answers

1. A two-sample t-test with equal number of observations per sample, would be the most appropriate statistical test to see if having breakfast improves the performance of the students. Rationale: We have two sets (samples) of scores - one set of students having breakfast and the other set of students not having breakfast. A good measure for comparison would be the average score of each set. Since population standard deviations are not known, t-distribution is appropriate.   

2. The independent variable in this study is having/not having breakfast.

3. The dependent variable in this study is the score in the math test.

4. Confounding factors, some of them at least, are: IQ of the student, hard-work put in by the student, physical status of the student on the test day. All these factors can marr/boost the effect of breakfast, if any.

5. Null hypothesis: Mean score of students having breakfast is the same as that of students not having breakfast. [Statistically, H0: µB = µA Vs HA: µB > µA , where µB = mean score of students having breakfast and µA = mean score of students of students not having breakfast]     

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