Choose the Correct Answer:

1.In hypothesis being tested about a population, "null" generally means "no difference" and thus refers to a situation in which no difference exists.

a. true b. false

2. It is an assertion or conjecture concerning one or more populations.

a. Alternative hypothesis b. Statistical hypothesis c. Null hypothesis d. Hypothesis

3. Which of the following assumptions is NOT made for the F test for comparing three or more means?

a. The variances of the populations must be equal. b. The samples must be independent of each other. c. The sample sizes must be equal. d. The populations from which the samples were obtained must be normally distributed.

4. A hypothesis test for which the rejection region lies at only one tail of the distribution is one-tailed test.

a. True b. False

5. When the null hypothesis is rejected, the alternative hypothesis is also rejected.

a. True b. False

6. Hypothesis test is an approach to statistical inference resulting in a decision to reject or not to reject the null hypothesis.

a. True b. False

7. Confidence interval is the interval computed from sample data that has a given probability that the unknown parameter, such as the mean or proportion, is contained within the interval.

a. True b. False

8. Statistical methods that make assumptions regarding the distribution of the observations is called distribution free.

a. True b. False

9. Confidence coefficient is the term in the formula for a confidence interval that determines probability level associated with the interval, such as 90%, 95%,and 99%.

a. True b. False

10. You are reading a manuscript that evaluates the impact of obesity on academic performance. The authors used a t-test to compare the baseline values of body mass index (BMI) in normal subjects and obese subjects. You are evaluating the use of a t-test to compare the BMI between the two groups. Which represents the most appropriate criteria to be met to use this parametric test for this particular evaluation?

a. The sample sizes in the normal and obese subjects must be equal to allow the use of a t-test.

b. The pre-study power should be at least 90%.

c. A t-test is not appropriate because BMI data are ordinal. d. The variance of the BMI data needs be similar in each group.

11. Mann Whitney U t-test applies to before-and-after measurements made on the same group of subjects.

a. True b. False

12. A researcher is comparing samples from 6 different populations. Assume that the conclusion from an ANOVA is that the null hypothesis is rejected, in other words that the 6 population means are not all equal. We should expect that

a. At least 6 of the comparisons of means would be significant

b. At least 3 of the comparisons of means would be significant

c. At least 1 of the comparisons of means would be significant

d. All 15 of the comparisons of means would be significant

13. You are evaluating a randomized, double-blind, parallel-group that compares four agencies for their efficiency on client satisfaction. The authors conclude that Agency A is better than Agency B (p<0.05) and that Agency C is better than Agency A (p<0.01), but no difference is observed between any other agencies. The investigators used an unpaired (independent samples)t-test to test the hypothesis that each agency was equal to the other. Which is most appropriate?

a. A paired t-test is a more appropriate test.

b. Agency B is the most efficient of these agencies.

c. Investigators used the appropriate statistical test to analyze their data.

d. ANOVA would have been a more appropriate test.

14. Directional test is also called one-tailed test.

a. True b. False

15. In the results of a randomized, double-blind, parallel group, controlled trial, it is reported that the difference in agency efficiency rates between the intervention group and the control group is 6% (p=0.01), and it is concluded that there is a statistically significant difference between the groups. Which statement is most consistent with this finding and these conclusions?

a. The chance of making a type I error is 5 in 100.

b. There is a high likelihood of having made a type II error.

c. The trial does not have enough power.

d. The chance of making an alpha error is 1 in 100.

16. F test is used in ANOVA.

a. True b. False

17 Nonparametric statistics are non-free distribution.

a. True b. False

18 Beta error is also called as type I error.

a. True b. False

18. The probability of incorrectly rejecting the null hypothesis in a test of hypothesis is called level of significance.

a. True b. False

19. Critical value is the value that a test statistic must exceed for the null hypothesis to be rejected.

a. True b. False