Question

E. Use the five-step hypothesis testing procedure below to determine if there is a difference in the mean weight changes of mice in the two groups. Use the alpha level you selected in part D. In StatKey, you are going to conduct a randomization test for the difference in means. This data is titled “Mice Wgt Gain-2e (Light vs Dark at Night).” Note that there are two similar data sets, use the one from the second edition of the book (i.e., “2e”). Be sure to include all relevant StatKey output. [30 points]

Step 1: Determine what type of test you need to conduct and write the hypotheses.

Step 2: Construct a randomization distribution under the assumption that the null hypothesis is true. Take at least 5000 resamples.

Step 3: Use the randomization distribution to find the p-value.

Step 4: Decide if you should reject or fail to reject the null hypothesis.

Step 5: State a real-world conclusion in relation to the original research question.

F. Compute Cohen’s d. (Hint: The pooled standard deviation is 2.378 grams). Remember to always show all work. [5 points]

G. Interpret the value of Cohen’s d that you computed in part F. [5 points]

Answer 1

1. The independent samples t-test would be appropriate here.

The hypothesis being tested is:

H₀: µ₁ = µ₂

H₁: µ₁ ≠ µ₂

2. The Statkey output is:

3. The p-value is 0.0787.

4. Since the p-value (0.0787) is greater than the significance level (0.05), we fail to reject the null hypothesis.

5. Therefore, we cannot conclude that there is a difference in the mean weight changes of mice in the two groups.

(f) Cohen's d = (6.578-4.306)/2.378 = 0.96

(g) This is a large effect.