1) (Chapter 10) Given the following t-statistics (23 ...



UNIVERSITY OF ILLINOIS

ECON173

SAMPLE MIDTERM

FALL, 2001

For selected questions, hints are provided in parenthesis. Answers are also provided. You might want to make a copy of the exam without hints and answers and work on that one first.

1) (Chapter 10) Given the following t-statistics (23 degrees of freedom) and p-values (1 tailed);

t-statistic: 1.7 ( p-value .05

t-statistic: 1.2 ( p-value .121

t-statistic: 2.1 ( p-value .023

What is the p-value for the t-statistic 1.3? --answer B

a) .141

b) .103

c) .042

d) .013

e) .461

(as the t-stat increases, the p-value should decrease)

2) When comparing the proportions of two populations, what type of test statistic is used? (chapter 12) --answer A

a) Z

b) T

c) F

d) All of the above

e) None of the above

3)(chapter 9)Given a population standard deviation of 13, a sample mean of 40, and a confidence interval width of 10, and a critical value of 1.645, what is the sample size? --answer B.

a) 4

b) 5

c) 6

d) 7

e) 8

(see page 303)

4) (chapter 10) If the p-value for a test is .4 then your decision is --answer C

a) There is sufficient evidence to conclude the alternative is correct.

b) There is sufficient evidence to conclude the null is correct.

c) There is insufficient evidence to conclude the alternative is correct.

d) There is insufficient evidence to conclude neither is correct.

e) None of the above

(golden rule: reject null if p-value is less than alpha, also, alpha is not likely to be bigger than 10%)

5)(chapter 10) Which of the following statements are equivalent? –answer c

I) Alpha

II) Beta

III) Probability of a Type I error

IV) Probability of a Type II error

V) Probability of Rejecting a true null

a) I and IV

b) I and III

c) I and III and V

d) II and V

e) II and IV and V

6) (chapter 10) The 95% confidence interval for the population average final exam score is [126.4, 195.5]. To test the claim that the average final exam score of the population is 180 at a 3% level of significance, what will be your decision? --answer B

a) Reject the null – conclude it is not 180

b) Fail to reject the null – insufficient evidence to conclude it is not 180

c) Reject the null – conclude it is 180

d) Fail to reject the null – sufficient evidence to conclude it is not 180

e) Cannot decide based on the given information

(to do the test you need a 97% C.I, which you don’t have, but you know that the price of a more confident interval is a WIDER interval)

7)(chapter 12) When doing a matched pairs test with differences distributed normally and unknown population standard deviation, which is the correct test statistic?

a) Equal variances pooled t test for means

b) Unequal variances pooled t test for means

c) Single population means test on the difference (*)

d) None of the above

e) Any of the above will work

8) (chapter 11) If you wish to know if more than 45% of the class scored above 70% on the exam, what is your null hypothosis? --answer B

a) H0: p=0.7

b) H0: p=0.45

c) H0: p>0.7

d) H0: p>0.45

e) Any of the above will work

9)(chapter 10) Suppose we are interested in whether the mean scores on the midterm for Economics 173 is below 80%. Given a p-value of .11 what is your conclusion?

a) Fail to reject the null at any reasonable level of significance (*)

b) Cannot determine based on the given information

c) Reject the null at any reasonable level of significance

d) Fail to reject the null only if the significance level is .01

e) Reject the null only if the significance level is .01

(again, it is not reasonable to set alpha to be more than 10%in most cases)

10)(chapter 11)Given the following list of observations: 1, 10, 34, 15, 8, 40, 90, 41, 5, 16. What proportion is above 8? --answer d

a) .4

b) .5

c) .6

d) .7

e) .8

11)(chapter 12) Before running an equal variances pooled t-test, what test should you run to formally decide if the needed assumptions are correct?

a) F-test for variances (*)

b) T-test for variances

c) Z-test for variances

d) No need to run a test

e) Eyeball test

12. A pharmaceutical company currently produces an anesthetic whose effective time is normally distributed with mean 7.4 and standard deviation 1.2. It is considering the launch of a new drug that they believe has a lower mean effective time but the same standard deviation. In a clinical study meant to test their belief, what would be the appropriate null and alternative hypothesis?

a. Ho: mu>=7.4, H1: mu7.4, H1: mu ................
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