13. -10.69 points MIntroStat9 7.E.082 My Notes Ask Your Teach A friend has perfo

Question

13. -10.69 points MIntroStat9 7.E.082 My Notes Ask Your Teach A friend has performed a significance test of the null hypothesis that two means are equal. His report states that the null hypothesis is rejected in favor of the alternative that the first mean is larger than the second. In a presentation on his work, he notes that the first sample mean was larger than the second mean and this is why he chose this particular one-sided alternative (a) Explain what is wrong with your friend's procedure and why O The null hypothesis in this case should have been that the first mean is larger than the second. We should only choose a one-sided alternative if we have some reason to expect a specific directional outcome before looking at the sample results O The first mean can never be larger than the second mean; this indicates a mistake was made during statistical analysis O We should never choose a one-sided alternative. O The null hypothesis in this case should have been that the two means were not equa (b) Suppose he reported t-1.70 with a P-value of 0.06. What is the correct P-value that he should report?

Explanation / Answer

(a) This should be a two-tailed test. This is because if the null hypothesis assumes that two means are equal, then the alternative hypothesis should state two means are not equal. In here he chooses the one-sided alternative, so it is not an appropiate test.So correct answer is "we should never choose a one-sided alternative"

(b)Since he performed the one-sided test, the p-value is 0.06.

If he performed the two tailed test, then the p value should be 0.06*2 = 0.12.

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