BSTAT5325 Exam 1 Version White, Summer, 2011

BSTAT5325 – Exam 1 Version White, Summer, 2011–

Solutions after question 25.
Blue version of exam follows the solutions to the white version.

What is a similarity between a hypothesis test question and a confidence interval question?

a. there are no similarities between them, only differences

b. both require you to find a rejection region value after calculating a z or t test

c. both require you to infer about a parameter based on the sample.

d. both require you to infer about the value of sample statistic.

2. When would you use the Tukey’s procedure?

a. if you wish to determine if any sample means differ

b. when Dr. Eakin says so. (Dr. Eakin says choose another answer.)

c. if you wish to estimate all possible differences in population means

d. when you wish to estimate the mean of a population based on t confidence interval

3. Which sampling procedures is used to obtain opinion data?

a. a t-test

b. an experiment

c. a confidence interval

d. a survey

4. To reduce or eliminate bias you should use a ______

a. a convenience sample

b. a random sample

c. a t-test

d. a judgment sample

5. If the population proportion is to be estimated but you only have sample data, you should use

a. a confidence interval based on a z if you have at least 30 observations.

b. a confidence interval based on a t if you have a small sample size.

c. a t-test on a population variance

d. a confidence interval based on a z if you have at least 5 successes and 5 failures.

6. In certain MBA programs, a student is required to have a large GMAT score before being accepted into the program. If the status quo is that a student should not be accepted. What would be the meaning of a type II error?

a. a student is not accepted into the program.

b. a student is accepted into the program but should not have been accepted.

c. a student is accepted.

d. a student is not accepted into the program but should have been.

7. Suppose you have a random sample of students who are taking a GMAT preparation class and a random sample who are not. One of the requirements of the F-test is the same variance. In terms of this problem, restate the equal variance assumption.

a. the course content is the same for both groups.

b. The variation in GMAT scores for the sample of students who take the GMAT preparation is the same as the variation of the sample of students students who do not take the preparation.

c. The variation in GMAT scores for all students who take the GMAT preparation is the same as the variation in all students who do not take the preparation.

d. The class content has the same variation before and after the GMAT is taken.

8. Your company makes light bulbs. Your current bulb lasts 1000 hours on average. You believe that a new bulb design will last longer on average. From a random sample of 30 new bulbs you calculate a t-test value of 1.45. What can you conclude?

a. There was sufficient information to say that there was an increase in average bulb life. The new bulb is better than the current one on average.

b. the new bulb is the same as the current one.

c. the new bulb is better than the old one.

d. while the bulb did last longer on average in the sample, there were not enough bulbs in the sample to detect an increase in average bulb life.

9. If a normally distributed population has a mean of 17 and a standard deviation of 3, What is the probability of finding a value larger than 20 using the empirical rule?

a. 84%

b. 2.5%

c. 16%

d. none of the other answers are correct

10. In the class notes, what is the symbol for the population proportion?

a. 

b

c. 

d.

11. You have randomly sampled75people and record the percent that made a purchase at Walmart in the last week. If you wish to estimate the percent of all people who make purchases at Walmart, you should use:

a. a t confidence interval for a population mean

b. a z confidence interval for a population proportion.

c. a Tukey confidence interval for the difference in population means

d. a giraffe

12. In which hypothesis will you always find the equal signs?

a. a type I error

b. the alternative

c. the rejection region

d. the null hypothesis

13. The probability associated with your test statistic is called the p-value. What is another name or symbol for the probability attached to the rejection region?

a. 

b

c. 

d.

14. When conducting a t-test, you obtain a t-test value of 12.34. What does the 12.34 indicate?

a. there were 12.34 sample standard errors between the values of the statistic and the hypothesized parameter

b. there is 12.34% chance the null hypothesis is correct

c. there were 12.34 standard deviations between the values of the mean and standard deviation

d. that I should have studied more (Hint: good conclusion, bad timing, wrong answer)

15. The ratio of the variability in sample means over their expected variability (if population means were equal) is called……?

a. the t-test

b. the F-test

c. the z-test

d. the q -test

16. What q table value would you use if you are taking 11 observations from each of two populations?

a. q(2,20)

b. q(1, 21)

c. q(2, 21)

d. none of the other answers are correct

17. Which is NOT one of the basic building blocks of this course?

a. sample estimates tend to miss the value of the parameter

b. to evaluate an error you need to know the standard error

c. statistics is always right

d. a random sample is required to reduce bias.

18. You have three random samples of 10 each. If you have an ANOVA F test statistic value of 3.10, would you reject equal means ? Why or why not?

a. No, because the F test statistic value is less than the F table value.

b. insufficient information to determine

c. Yes, because the F test statistic value is greater than the F table value.

d. Yes, because the F test statistic value is less than the F table value

19. If two sample means are equal, can we conclude that their population means are also equal?

a. Yes

b. Maybe

c. more information is needed

d. No

20. What is the standard deviation of the following population of numbers? (3, 4, 7, 14)

a. 67.5

b. none of the other answers are correct

c. 4.967

d. 4.301

21. If you have a sample of 20 observations, what is the rejection region when trying to show that the population mean is less than 100? Reject Ho if

a. t > 2.094 or t < -2.093

b. Z < 1.645

c. none of the other answers are correct

d. t < -1.7291

22. Different factors could affect a student’s test grade. If you could set up an experiment, what would be one possible factor you would use?

a. undergraduate major

b. the grade

c. a sample

d. the F test

23. Sample means do not equal the population mean for continuous data. They have a margin of error. What is another way of describing a margin of error?

a. the standard error of the sample mean

b. the chance that the values of the population are within a specified distance of the sample mean.

c. the standard deviation of the population of data

d. the largest error you would expect in the sample mean for a specified probability

24. You have a random sample of 5 objects from each of 2 populations. If the variation of random data (MSE) is 25, what would the largest error you would expect when estimating the average of population 1 minus the average of population 2?

a. 8.247

b. 2.530

c. 8.095

d. none of the other answers are correct

25. If n=100 and the population proportion is 0.20, what is the standard error of the sample proportion?

a. 0.0400

b. 0.0784

c. 0.1600

d. none of the other answers are correct

WhiteKeyPartial Credit

6D1/4 credit for b

7C1/2 credit for b

8D1/2 credit for a

10C

11B1/2 credit for a

12D

WhiteKeyPartial Credit

13D

14A

15B

16A

17C

18A

19B or D

20D

21D

22A

23D1/4 credit for b

24D

25A

BSTAT5325 – Exam 1 Version Blue, Summer, 2011

1. In certain MBA programs, a student is required to have a large GMAT score before being accepted into the program. If the status quo is that a student should not be accepted. What would be the meaning of a type II error?

a. a student is accepted.

b. a student is not accepted into the program but should have been.

c. a student is not accepted into the program.

d. a student is accepted into the program but should not have been accepted.

2. The ratio of the variability in sample means over their expected variability (if population means were equal) is called……?

a. the z-test

b. the q -test

c. the t-test

d. the F-test

3. Suppose you have a random sample of students who aretaking a GMAT preparation class and a random sample who are not. One of the requirements of the F-test is the same variance. In terms of this problem, restate the equal variance assumption.

a. The variation in GMAT scores for all students who take the GMAT preparation is the same as the variation in all students who do not take the preparation.

b. The class content has the same variation before and after the GMAT is taken.

c. the course content is the same for both groups.

d. The variation in GMAT scores for the sample of students who take the GMAT preparation is the same as the variation of the sample of students students who do not take the preparation.

4.In the class notes, what is the symbol for the population proportion?

a. 

b.

c. 

d

5. In which hypothesis will you always find the equal signs?

a. the rejection region

b. the null hypothesis

c. a type I error

d. the alternative

6. When conducting a t-test, you obtain a t-test value of 12.34. What does the 12.34 indicate?

a. there were 12.34 standard deviations between the values of the mean and standard deviation

b. that I should have studied more (Hint: good conclusion, bad timing, wrong answer)

c. there were 12.34 sample standard errors between the values of the statistic and the hypothesized parameter

d. there is 12.34% chance the null hypothesis is correct

7. If a normally distributed population has a mean of 17 and a standard deviation of 3, What is the probability of finding a value larger than 20 using the empirical rule?

a. 16%

b. none of the other answers are correct

c. 84%

d. 2.5%

8. What q table value would you use if you are taking 11 observations from each of two populations?

a. q(2, 21)

b. none of the other answers are correct

c. q(2,20)

d. q(1, 21)

9. If n=100 and the population proportion is 0.20, what is the standard error of the sample proportion?

a. 0.1600

b. none of the other answers are correct

c. 0.0400

d. 0.0784

10. Which sampling procedures is used to obtain opinion data?

a. a confidence interval

b. a survey

c. a t-test

d. an experiment

11. You have three random samples of 10 each. If you have an ANOVA F test statistic value of 3.10, would you reject equal means ? Why or why not?

a. Yes, because the F test statistic value is greater than the F table value.

b. Yes, because the F test statistic value is less than the F table value

c. No, because the F test statistic value is less than the F table value.

d. insufficient information to determine

12. To reduce or eliminate bias you should use a ______

a. a t-test

b. a judgment sample

c. a convenience sample

d. a random sample

13. If you have a sample of 20 observations, what is the rejection region when trying to show that the population mean is less than 100? Reject Ho if

a. none of the other answers are correct

b. t < -1.7291

c. t > 2.094 or t < -2.093

d. Z < 1.645

14. Different factors could affect a student’s test grade. If you could set up an experiment, what would be one possible factor you would use?

a. a sample

b. the F test

c. undergraduate major

d. the grade

15. If two sample means are equal, can we conclude that their population means are also equal?

a. more information is needed

b. No

c. Yes

d. Maybe

16. When would you use the Tukey’s procedure?

a. if you wish to estimate all possible differences in population means

b. when you wish to estimate the mean of a population based on t confidence interval

c. if you wish to determine if any sample means differ

d. when Dr. Eakin says so. (Dr. Eakin says choose another answer.)

17. Which is NOT one of the basic building blocks of this course?

a. statistics is always right

b. a random sample is required to reduce bias.

c. sample estimates tend to miss the value of the parameter

d. to evaluate an error you need to know the standard error

18. What is a similarity between a hypothesis test question and a confidence interval question?

a. both require you to infer about a parameter based on the sample.

b. both require you to infer about the value of sample statistic.

c. there are no similarities between them, only differences

d. both require you to find a rejection region value after calculating a z or t test

19. The probability associated with your test statistic is called the p-value. What is another name or symbol for the probability attached to the rejection region?

a. 

b.

c. 



20. If the population proportion is to be estimated but you only have sample data, you should use

a. a t-test on a population variance

b. a confidence interval based on a z if you have at least 5 successes and 5 failures.

c. a confidence interval based on a z if you have at least 30 observations.

d. a confidence interval based on a t if you have a small sample size.

21. Your company makes light bulbs. Your current bulb lasts 1000 hours on average. You believe that a new bulb design will last longer on average. From a random sample of 30 new bulbs you calculate a t-test value of 1.45. What can you conclude?

a. the new bulb is better than the old one.

b. while the bulb did last longer on average in the sample, there were not enough bulbs in the sample to detect an increase in average bulb life.

c. There was sufficient information to say that there was an increase in average bulb life. The new bulb is better than the current one on average.

d. the new bulb is the same as the current one.

22. What is the standard deviation of the following population of numbers? (3, 4, 7, 14)

a. 4.967

b. 4.301

c. 67.5

d. none of the other answers are correct

23. You have randomly sampled75people and record the percent that made a purchase at Walmart in the last week. If you wish to estimate the percent of all people who make purchases at Walmart, you should use

a. a Tukey confidence interval for the difference in population means

b. a giraffe

c. a t confidence interval for a population mean

d. a z confidence interval for a population proportion.

a. 8.095

b. none of the other answers are correct

c. 8.247

d. 2.530

25. Sample means do not equal the population mean for continuous data. They have a margin of error. What is another way of describing a margin of error?

a. the standard deviation of the population of data

b. the largest error you would expect in the sample mean for a specified probability

c. the standard error of the sample mean

d. the chance that the values of the population are within a specified distance of the sample mean.

BluekeyPartial Credit

1B1/4 credit for d

3A1/2 credit for d

10B

11C

12d

BluekeyPartial Credit

13B

14C

15B or D

16A

17A

18A

19B

20B

21B1/2 credit for c

22B

23d1/2 credit for c

24B

25B¼ credit for d