Question

8. A random sample of 25 college males was obtained and each was asked to report their actual height and what they wished as their ideal height. A 95% confidence interval for μd= average difference between their ideal and actual heights was 0.8" to 2.2". Based on this interval, which one of the null hypotheses below (versus a two-sided alternative)can be rejected?

A. H0: μd= 0.5

B. H0: μd= 1.0

C. H0: μd= 1.5

D. H0: μd= 2.0

9. The average time in years to get an undergraduate degree in computer science was compared for men and women.

Random samples of 100 male computer science majors and 100 female computer science majors were taken. Choose

the appropriate parameter(s) for this situation.

A. One population proportion p.

B. Difference between two population proportions p1− p2

C. One population mean μ

D. Difference between two population means μ1−μ2

10. If the word significant is used to describe a result in a news article reporting on a study,

A. the p-value for the test must have been very large.

B. the effect size must have been very large.

C. the sample size must have been very small.

D. it may be significant in the statistical sense, but not in the everyday sense.

11. A significance test based on a small sample may not produce a statistically significant result even if the true value

differs substantially from the null value. This type of result is known as

A. the significance level of the test.

B. the power of the study.

C. a Type 1 error.

D. a Type 2 error.

12. One problem with hypothesis testing is that a real effect may not be detected. This problem is most likely to occur

when

A. the effect is small and the sample size is small.

B. the effect is large and the sample size is small.

C. the effect is small and the sample size is large.

D. the effect is large and the sample size is large.

For the next two questions (13 and 14): It is known that for right-handed people, the dominant (right) hand tends to be stronger. For left-handed people who live in a world designed for right-handed people, the same may not be true. To test this, muscle strength was measured on the right and left hands of a random sample of 15 left-handed men and the difference (left- right) was found. The alternative hypothesis is one-sided (left hand stronger). The resulting t-statistic was 1.80.

13. This is an example of:

A. A two-sample t-test.

B. A paired t-test.

C. A pooled t-test.

D. An unpooled t-test.

14. Assuming the conditions are met, based on the t-statistic of 1.80 the appropriate conclusion for this test using α =.05 is:

A. df = 14, so p-value < .05 and the null hypothesis can be rejected.

B. df = 14, so p-value > .05 and the null hypothesis cannot be rejected.

C. df = 28, so p-value < .05 and the null hypothesis can be rejected.

D. df = 28, so p-value > .05 and the null hypothesis cannot be rejected.

15. A test of H0: μ≤0 versus Ha: μ > 0 is conducted on the same population independently by two different researchers. They both use the same sample size and the same value of α = 0.05. Which of the following will be the same for both researchers?

A. The p-value of the test.

B. The power of the test if the true μ = 6.

C. The value of the test statistic.

D. The decision about whether or not to reject the null hypothesis.

16. Which of the following is NOT a correct way to state a null hypothesis?

B. Ho: μ,-10 D. Ho: p = .5

Answer 1

8. Confidence interval = (0.8, 2.2)

Answer A:

We will reject A because this mean value is not in the confidence interval.

9. As average time is given we will use mean.

Answer D: Difference between two population means $\mu_1-\mu_2$

10. Answer D: It may be significant in the statistical sense, but not in the everyday sense.

11. Answer D : a type 2 error

12. Answer A : The effect is small and the sample size is small.

13. Answer B : A paired t-test.

As same set of sample is used for both test

14. At df= 14 and t = 1.80, p-value = 0.047

Answer A : df = 14, so p-value < .05 and the null hypothesis can be rejected.

15. Answer D : The decision about whether or not to reject the null hypothesis.

16. Answer A : $H_o:\hat p_1-\hat p_2=0$