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Describe the four distinct possible outcomes of a null hypothesis test. In your description, explain how these outcomes are created by the intersection of the researcher's formal decisions and the possible states of reality, and identify which two outcomes are correct decisions and which two are statistical errors.
Question: Describe the four distinct possible outcomes of a null hypothesis test. In your description, explain how these outcomes are created by the intersection of the researcher's formal decisions and the possible states of reality, and identify which two outcomes are correct decisions and which two are statistical errors.
Sample answer: The four possible outcomes are created by the intersection of two decisions a researcher can make (to reject or retain the null hypothesis) and two states of reality (the null hypothesis is actually true or false). The two correct decisions are rejecting a false null hypothesis and retaining a true null hypothesis. The two statistical errors are rejecting a true null hypothesis (which is a Type I error) and retaining a false null hypothesis (which is a Type II error).
Key points:
- Researchers formally decide to either reject or retain the null hypothesis.
- The state of reality is that the null hypothesis is either true or false.
- Correct decision: Rejecting a false null hypothesis.
- Correct decision: Retaining a true null hypothesis.
- Statistical error (Type I error): Rejecting a true null hypothesis.
- Statistical error (Type II error): Retaining a false null hypothesis.
Rubric: A full credit response must explicitly identify the two possible researcher decisions, the two states of reality, the two specific correct decisions, and the two specific statistical errors (Type I and Type II).
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Research Methods in Psychology - 4th American Edition @ KPU
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