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A clinical psychology researcher wants to test whether an intervention reduces anxiety scores below the national average. The hypothetical population mean anxiety score is . After the intervention, a sample of participants has a mean anxiety score of with a sample standard deviation of . Using the one-sample -test formula , calculate the statistic. Show your work step-by-step and explain how the numerator and the denominator each contribute to the final calculated value.
Question: A clinical psychology researcher wants to test whether an intervention reduces anxiety scores below the national average. The hypothetical population mean anxiety score is . After the intervention, a sample of participants has a mean anxiety score of with a sample standard deviation of . Using the one-sample -test formula , calculate the statistic. Show your work step-by-step and explain how the numerator and the denominator each contribute to the final calculated value.
Sample answer: First, I calculate the numerator: . This represents the difference between our sample mean and the hypothetical population mean. Next, I calculate the denominator, which represents the standard error: . Finally, I divide the numerator by the denominator to get the statistic: . The numerator shows the absolute difference between the sample and the population, while the denominator accounts for the variability and sample size.
Key points:
- Calculates the numerator as 44 - 50 = -6.
- Calculates the denominator as 10 / 5 = 2.
- Calculates the final t-statistic as -6 / 2 = -3.00.
- Explains the numerator reflects the absolute difference from the hypothetical population mean.
- Explains the denominator reflects the standard error or variability relative to the sample size.
Rubric: The essay should correctly calculate the numerator (-6), the denominator (2), and the final t-statistic (-3). It should also briefly explain that the numerator measures the mean difference and the denominator measures expected variability based on standard deviation and sample size.
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Research Methods in Psychology - 4th American Edition @ KPU
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