QUESTION 1

The table below contains the level of carboxyhemoglobin (in %) from two independent randomly selected groups of subjects, a group of non-smokers and a group of smokers. At 5% level of significance, test to see if the mean carboxyhemoglobin level of the smokers is significantly different from the mean of the nonsmokers.

Data: (Carboxyhemoglogin (%))

Non-smokers: 1.13, 3.70, 1.45, 4.11, 2.91, 0.91

Smokers: 5.33, 3.58, 4.69, 2.77, 4 .54, 6.49

Which of the following statement is correct?

	A.	Two independent samples t-test can be used for this analysis if both samples of measurements are normally distributed.
	B.	One sample t-test can be used for this analysis if the paired differences are normally distributed.
	C.	Paired sample t-test can be used for this analysis if the paired differences are normally distributed.
	D.	Two independent samples t-test can be used for this analysis if the paired differences are normally distributed.

3 points

QUESTION 2

The table below contains the level of carboxyhemoglobin (in %) from two independent randomly selected groups of subjects, a group of non-smokers and a group of smokers. At 5% level of significance, we want totest to see if the mean carboxyhemoglobin level of the smokers is significantly different from the mean of the nonsmokers.

Data: (Carboxyhemoglogin (%))

Non-smokers: 1.13, 3.70, 1.45, 4.11, 2.91, 0.91

Smokers: 5.33, 3.58, 4.69, 2.77, 4.54, 6.49

Which of the following statements is correct p-value for this test? (Perform the test assuming there is no significant difference in the variances of the two sampled populations.)

	A.	0.8966
	B.	0.00892
	C.	0.01785
	D.	0.01792

3 points

QUESTION 3

The table below contains the level of carboxyhemoglobin (in %) from two independent randomly selected groups of subjects, a group of non-smokers and a group of smokers. At 5% level of significance, test to see if the mean carboxyhemoglobin level of the smokers is significantly different from the mean of the nonsmokers.

Data: (Carboxyhemoglogin (%))

Non-smokers: 1.13, 3.70, 1.45, 4.11, 2.91, 0.91

Smokers: 5.33, 3.58, 4.69, 2.77, 4.54, 6.49

Which of the following statement(s) is(are) correct? (There are more than one correct answer.)

	A.	The null hypothesis would be rejected.
	B.	It is a two-sided test.
	C.	It is a one-sided test.
	D.	The null hypothesis would not be rejected.

3 points

QUESTION 4

A group of researchers wish to test whether there is significant difference between the average blood pressures of two different populations. The p-value reported by these researchers from using a two-sample t-test was 0.1. Which of the following statements is correct?

	A.	The difference between the average blood pressures of these two populations is statistically significant at 5% level of significance.
	B.	The difference between the average blood pressures of these two populations is statistically significant at 1% level of significance.
	C.	The difference between the average blood pressures of these two populations is statistically significant at 0.1% level of significance.
	D.	The difference between the average blood pressures of these two populations is statistically insignificant at 5% level of significance.

3 points

QUESTION 5

In a research study, blood samples were taken from two different locations of human's body, arm and finger tip. The goal is to compare the blood glucose readings to see if there is a difference between the average readings from these two parts of a human body. Ten subjects, healthy adults, were randomly selected and the blood samples from both locations were taken from each subject. Researchers wish to use a statistical test to compare whether there is a significant different between the blood glucose readings for blood sampled from the two different locations. Which procedure would you recommend? (Choose one answer)

	A.	One sample z-test for one population proportion.
	B.	Paired sample t-test for difference between two means.
	C.	Two samples z-test for difference between two means.
	D.	Chi-square test for independence.

3 points

QUESTION 6

A team of researchers is investigating a drug for reducing systolic blood pressure. A group of 6 subjects was selected in this study. The systolic blood pressures were measured before and after the treatment with this drug and are listed the table above. This team wishes to test "whether there is a statistically significant reduction in blood pressure after the use of the drug treatment". Which of the following conclusions is(are) correct using a t-test?

Subject ID	1	2	3	4	5	6
Before	144	152	155	149	151	148
After	143	152	148	145	144	147

	A.	The null hypothesis is that there is no statistically significant reduction in blood pressure after the use of the drug treatment.
	B.	The alternative hypothesis is that there is statistically significant increase in blood pressure after the use of the drug treatment.
	C.	The null hypothesis is that there is statistically significant reduction in blood pressure after the use of the drug treatment.
	D.	The alternative hypothesis is that there is no statistically significant reduction in blood pressure after the use of the drug treatment.

3 points

QUESTION 7

A team of researchers is investigating a drug for reducing systolic blood pressure. A group of 6 subjects was selected in this study. The systolic blood pressures were measured before and after the treatment with this drug and are listed below. This team wishes to test whether there is a statistically significant reduction in blood pressure after the use of the drug treatment. If the assumption of normality is accepted, which of the following conclusions is(are) correct using a t-test?

Subject ID	1	2	3	4	5	6
Before	144	152	155	149	151	148
After	143	152	148	145	144	147

	A.	The p-value of the test is .048.
	B.	The p-value of the test is .096.
	C.	The p-value of the test is .024.
	D.	The p-value of the test is .012.

3 points

QUESTION 8

In a study, researchers wish to understand the difference between four training programs to train individuals for a new task. Twelve subjects with similar ability were randomly selected from several health departments in Ohio. Training programs were randomly assigned to the twelve subjects so that each program has three subjects. The evaluations on proficiency of these twelve subjects in performing this new task were recorded as in the following table. The higher the score the better the performance.

Program 1	Program 2	Program 3	Program 4
23	34	16	17
25	38	23	20
26	31	24	21

Which statistical test can be used for testing whether this is significant difference between four programs?

	A.	Two Way ANOVA Analysis
	B.	One Way ANOVA Analysis
	C.	Paired Sample t-Test
	D.	Two Independent Samples t-Test
	E.	Chi-square Test for Independence

3 points

QUESTION 9

A team of researchers is investigating a drug for reducing systolic blood pressure. Three groups each has 6 subjects were selected in this study. Group A is the control group. The treatment was used for group B. A fixed increased amount of doses were used on group C. The systolic blood pressures were measured for all groups and are listed above. This team wishes to test whether there is a statistically significant difference in average systolic blood pressures between the three groups. If the assumption of normality and equal variances is accepted, which of the following conclusions is correct from the ANOVA F-test?

Group A	144	152	155	149	151	148
Group B	143	152	148	145	144	147
Group C	140	144	140	138	135	139

	A.	p-value is less than .001. There is statistically significant difference between treatments.
	B.	p-value is 15.452. There is no statistically significant difference between treatments.
	C.	p-value is between .01 and .05. There is statistically significant difference between treatments.
	D.	p-value is greater than .05. There is no statistically significant difference between treatments.

3 points

QUESTION 10

A team of researchers is investigating a drug for reducing systolic blood pressure. Three groups each has 6 subjects were selected in this study. Group A is the control group. The treatment was used for group B. A fixed increased amount of doses were used on group C. The systolic blood pressures were measured for all groups and are listed above. This team wishes to test whether there is a statistically significant difference in average systolic blood pressures between the three groups. If the assumption of normality and equal variances is accepted, which of the following conclusions is correct from the multiple comparisons t-test using Bonferroni correction at 5% level of significance? (Check all correct answers. There is more than one correct answers.)

Group A	144	152	155	149	151	148
Group B	143	152	148	145	144	147
Group C	140	144	140	138	135	139

	A.	There is statistically significant difference between groups A and C.
	B.	There is no statistically significant difference between groups B and C.
	C.	There is no statistically significant difference between groups A and B.
	D.	There is statistically significant difference between groups A and B.