Short Answer

Suppose you are evaluating a tt score of 1.501.50 with 2424 degrees of freedom. If you know that the proportion of expected tt scores that are 1.501.50 or greater is .07.07, apply the two-tailed definition of "extreme" to determine both the proportion of expected scores that are 1.50-1.50 or lower and the final combined pp-value.

Question: Suppose you are evaluating a tt score of 1.501.50 with 2424 degrees of freedom. If you know that the proportion of expected tt scores that are 1.501.50 or greater is .07.07, apply the two-tailed definition of "extreme" to determine both the proportion of expected scores that are 1.50-1.50 or lower and the final combined pp-value.

Sample answer: Because the distribution is symmetric, the proportion of expected tt scores that are 1.50-1.50 or lower is also .07.07. Combining these two proportions (.07+.07.07 + .07) yields a final pp-value of .14.14.

Key points:

  • State that the proportion of expected tt scores that are 1.50-1.50 or lower is .07.07.
  • Combine the positive and negative tail proportions (.07+.07.07 + .07).
  • Calculate the final pp-value as .14.14.

Rubric: The answer should state that the proportion of expected scores that are 1.50-1.50 or lower is .07.07, and combine the two tails to calculate a final pp-value of .14.14.

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Updated 2026-05-27

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Research Methods in Psychology - 4th American Edition @ KPU

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