# STA 698

Question 2 of 10Medical researchers studying two therapies for treating patients infected with Hepatitis C found the following data. Assume a .05 significance level for testing the claim that the proportions are not equal. Also, assume the two simple random samples are independent and that the conditions np ≥ 5 and nq ≥ 5 are satisfied.

Therapy 1

Therapy 2

Number of patients

39

47

Eliminated Hepatitis

20

13

C infection

Construct a 95% confidence interval estimate of the odds ratio of the odds for having Hepatitis C after Therapy 1 to the odds for having Hepatitis C after Therapy 2. Give your answer with two decimals, e.g., (12.34,56.78)

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3.Scientists, researching large woody debris (LWD), surveyed the number of LWD pieces from aerial photos taken annually for the past 35 years at two different sites. Over the 35 years of photos examined, the first site had a mean number of LWD pieces per hectare per year (LWD/ha/yr) of 3.7 pieces with a standard deviation of 1.9. The second site had a mean number of LWD/ha/yr of 4.3 with a standard deviation of 2.4. Assume a .05 significance level for testing the claim that the mean LWD/ha at the first site had less than the mean LWD/ha/yr at the second site. Also, assume the two samples are independent simple random samples selected from normally distributed populations, but do not assume that the population standard deviations are equal.

Construct a 90% confidence interval for the difference between the two means. Give your answer with two decimals, e.g., (12.34,56.78)

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4.The paired data consist of the cost of regionally advertising (in thousands of dollars) a certain pharmaceutical drug and the number of new prescriptions written (in thousands).

Cost

9

2

3

4

2

5

9

10

Number

85

52

55

68

67

86

83

73

Find the value of the linear correlation coefficient r . Give your answer to three decimals, e.g., .987 .

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5.Use a .05 significance level and the observed frequencies of 144 drownings at the beaches of a randomly selected coastal state to test the claim that the number of drownings for each month is equally likely.

Jan

Feb

Mar

Apr

May

June

July

Aug

Sept

Oct

Nov

Dec

1

3

2

7

14

20

37

33

16

6

2

3

Determine the value of the χ2 test statistic. Give your answer to two decimals, e.g., 12.34

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6.Using a .01 significance level, test the claim that the proportions of fear/do not fear responses are the same for male and female dental patients.

Gender

Male

Female

Fear Dentistry

48

70

Do Not Fear Dentistry

21

32

Do you reject the null hypothesis, at the .01 significance level? Enter Y for yes (reject), N for no (fail to reject).

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Question 7 of 10 The table represents results from an experiment with patients afflicted with eczema on both arms. Each patient was treated with an immune modulator cream on one arm and a topical steroid cream on the other arm. Using a .05 significance level, apply McNemar’s test to test the following claim: The proportion of patients with no cure on the immune modulator treated arm and a cure on the topical steroid treated arm is the same as the proportion of patients with a cure on the immune modulator treated arm and no cure on the topical steroid treated arm.

Immune Modulator Cream

Cure

No Cure

Topical Steroid

Cure

25

11

Cream

No Cure

42

22

Do you reject the null hypothesis, at the .05 significance level? Enter Y for yes (reject), N for no (fail to reject).

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Question 8 of 10 For a study on Type 1 diabetes, medical graduate students subdivided the United States into four study regions (Northeast, Southeast, Southwest, and Northwest). The students randomly selected seven patients per region and recorded the number of times during a randomly selected month that each patient used insulin shots to regulate blood sugar levels. Use One-Way ANOVA at a .05 significance level to test the claim that the means from the different regions are not the same.
Mean number of times patients used insulin shots to regulate blood sugar levels

Northeast

Southeast

Southwest

Northwest

4

6

4

4

3

5

5

4

3

6

6

5

4

8

6

6

3

6

7

3

2

6

5

5

5

8

4

3

Do you reject the null hypothesis, at the .05 significance level? Enter Y for yes (reject), N for no (fail to reject).

Question 9 of 10For a Two-Way ANOVA, assuming there is not an interaction, we can continue to interpret the results of the row and column effects.

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[removed]   False

10.Use the following technology display from a Two-Way ANOVA to answer this question. Biologists studying habitat use in Lepidopteran moths measured the number of savannah moths found at three randomly selected prairie sites with two potential habitat interferences (expansion of row crops and grazing). Use a .05 significance level.

Source

Df

SS

MS

F

P

Site

2

.1905

.0952

.0381

.9627

Habitat

1

304.0238

304.0238

121.6095

.0000

Site*Habitat

2

.1905

.0952

.0381

.9627

Do you reject the null hypothesis about the site effect, at the .05 significance level? Enter Y for yes (reject), N for no (fail to reject).