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Explain whether the student should reject or retain the null hypothesis based on this critical value. What does this decision indicate about the population relationship between the variables, and what can be concluded about the pp-value?

Case context: A psychology student is manually calculating a correlation coefficient for a study involving 22 participants. She calculates a sample correlation coefficient of r=.38r = .38. Looking up Table 13.5 for 222=2022 - 2 = 20 degrees of freedom, she finds the critical value is .444 at the α=.05\alpha = .05 level.

Question: Explain whether the student should reject or retain the null hypothesis based on this critical value. What does this decision indicate about the population relationship between the variables, and what can be concluded about the pp-value?

Sample answer: The student should retain the null hypothesis because the calculated sample correlation of r=.38r = .38 is less extreme than the critical value of .444. This indicates that the pp-value is greater than .05, and there is insufficient evidence to conclude that a relationship exists in the population.

Key points:

  • State that the null hypothesis should be retained.
  • Compare the calculated r=.38r = .38 to the critical value .444 and note that it is less extreme.
  • Indicate that the pp-value is greater than .05.
  • Conclude that there is insufficient evidence of a relationship in the population.

Rubric: The response must correctly state that the student should retain the null hypothesis, note that the sample correlation (r=.38r = .38) is less extreme than the critical value (.444), specify that the pp-value is greater than .05, and conclude there is insufficient evidence of a relationship in the population.

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Updated 2026-05-26

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Research Methods in Psychology - 4th American Edition @ KPU

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