Week#7 Statistics
Note: When you answer questions involving the test of hypotheses, use the four-step hypothesis process (see textbook pages 298-299).
Also, see your textbook for the full question when necessary; the chapter 9 problems start on p. 303
Chapter 9, problems 4, 12, 14, 22
4. Explain why t distributions tend to be flatter and more spread out than the normal distribution.
12. Last fall, a sample of n = 36 freshmen was selected to participate in a new 4-hour training program designed to improve study skills…: = 74; M = 79.4, s = 18.
a. On the basis of these data, can the college conclude that the students in the new program performed significantly better than the rest of the freshman class? Use a one-tailed test with = .05.
b. Can the college conclude that the students in the new program are significantly different from the rest of the freshman class? Use a two-tailed test with = .05.
14. In the Preview for this chapter, we discussed a study that examined the effect of eye spot patterns on the behavior of moth eating birds: = 30; M = 37, SS = 288, n = 9.
a. Is this sample sufficient to conclude that the eye-spots have a significant influence on the birds’ behavior? Use a two-tailed test with = .05.
b. Compute the estimated Cohen’s d to measure the size of the treatment effect.
22. A researcher would like to examine the effects of humidity on eating behavior. It is known that laboratory rats normally eat an average of = 21 grams of food each day. The researcher selects a random sample of n = 16 rats and places them in a controlled atmosphere room in which the relative humidity is maintained at 90%. The daily food consumption scores for the rats are as follows:
14, 18, 21, 15, 18, 18, 21, 18, 16, 20, 17, 19, 20, 17, 17, 19
a. Can the researcher conclude that humidity has a significant effect on eating behavior? Use a two-tailed test with = .05.
b. Compute the estimated d and r2 to measure the size of the treatment
Also, see your textbook for the full question when necessary; the chapter 9 problems start on p. 303
Chapter 9, problems 4, 12, 14, 22
4. Explain why t distributions tend to be flatter and more spread out than the normal distribution.
12. Last fall, a sample of n = 36 freshmen was selected to participate in a new 4-hour training program designed to improve study skills…: = 74; M = 79.4, s = 18.
a. On the basis of these data, can the college conclude that the students in the new program performed significantly better than the rest of the freshman class? Use a one-tailed test with = .05.
b. Can the college conclude that the students in the new program are significantly different from the rest of the freshman class? Use a two-tailed test with = .05.
14. In the Preview for this chapter, we discussed a study that examined the effect of eye spot patterns on the behavior of moth eating birds: = 30; M = 37, SS = 288, n = 9.
a. Is this sample sufficient to conclude that the eye-spots have a significant influence on the birds’ behavior? Use a two-tailed test with = .05.
b. Compute the estimated Cohen’s d to measure the size of the treatment effect.
22. A researcher would like to examine the effects of humidity on eating behavior. It is known that laboratory rats normally eat an average of = 21 grams of food each day. The researcher selects a random sample of n = 16 rats and places them in a controlled atmosphere room in which the relative humidity is maintained at 90%. The daily food consumption scores for the rats are as follows:
14, 18, 21, 15, 18, 18, 21, 18, 16, 20, 17, 19, 20, 17, 17, 19
a. Can the researcher conclude that humidity has a significant effect on eating behavior? Use a two-tailed test with = .05.
b. Compute the estimated d and r2 to measure the size of the treatment