. a sample from a Normal population with mean u = 20 and standard deviation o = 2.5 failed to reject the null hypothesis Ho: = 17.5 at the a = 0.05 significance level. Enter the information from this example into the Statistical Power applet. (Don't forget that the alternative hypothesis is two-sided.) What is the power of the test against the alternative M # 17.5?
1. a sample from a Normal population with mean u = 20 and standard deviation o = 2.5 failed to reject the null hypothesis Ho: = 17.5 at the a = 0.05 significance level. Enter the information from this example into the Statistical Power applet. (Don't forget that the alternative hypothesis is two-sided.) What is the power of the test against the alternative M # 17.5?
2. You read in the report of a psychology experiment: "Separate analyses for our two groups of 12 participants revealed no overall placebo effect for our student group (mean = 0.08, SD = 0.37, 4 = 0,49)
and a significant effect for our nonstudent group (mean = 0.35, SD = 0.37, ¢u = 3.25, p < 0.01). 'IS The null hypothesis is that the mean effect is zero. What are the correct values of the two t statistics based on the means and standard deviations? Compare each correct talue with the critical values in Table C. What can you say about the twosided Pvalue in each case?
3. Do wearable devices that monitor diet and physical activity help people lose weight? Researchers had 237 subjects who were already involved in a program of diet and exercise use wearable technology for 24 months.They measured their weight (in kilograms) before using the technology and 24 months after using the technology.18
- Explain why the proper procedure to compare the mean weight before using the wearable technology and 24 months after using the wearable technology is a matched pairs t test.
- The 237 differences in weight (weight after 24 months minus weight before using the wearable technology) had › = -3.5 and s= 7.8. Is there significant evidence of a reduction in weight after using the wearable technology?
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