Solved by a verified expert:·

Question 1

Match the following:

o

__B__Prognostic Factor

B. Strongly associated with outcome

__G__Prospective

G. Study looking forward in time

__D__Quasi-experimental

D. No random assignment

__E__Retrospective

E. Study looking backward in time

__I__Stratification

I. Subjects assigned to non overlapping groups

__A__Case control study

A. Subjects identified based on outcome status

__H__Missclassification bias

H. Outcome or exposure classification error

__J__RCT

C. Subjects receive two or more treatments.

__C__Crossover Trial

J. Subject randomly assigned to treatment groups

__F__Washout period

F. Time when no treatment occurs

·

Question 2

An investigator wants to assess

whether the use of a specific medication given to infants born prematurely is

associated with developmental delay. Fifty infants who were given the

medication and fifty comparison infants who were also born prematurely but

not given the medication will be selected for the analysis. Each infant

will undergo extensive testing at age 2 for various aspects of development.

Identify the type of study proposed and indicate its specific strengths

and weaknesses.

Type of study:

Strengths:

Weaknessess:

·

Question 3

In 1940, 2,000 women working in a

factory were recruited into a study. Half of the women worked in

manufacturing and half in administrative offices. The incidence of bone

cancer through 1970 among the 1,000 women working in manufacturing was

compared with that of 1,000 women working in administrative offices.

Thirty of the women in manufacturing developed bone cancer as compared

to 9 of the women in administrative offices. This study is an example

of a:

___ __

study

·

Question 4

A clinical trial is conducted to

evaluate the effectiveness of a new drug to prevent preterm delivery. A

total of n=250 pregnant women agree to participate and are randomly assigned

to receive either the new drug or a placebo and followed through the course

of pregnancy. Among 125 women receiving the new drug, 24 deliver

preterm and among 125 women receiving the placebo, 38 deliver preterm.

Construct a 95% confidence interval for the difference in proportions

of women who deliver preterm.

1.Upper Limit CI=

2.Lower Limt CI =

·

Question 5

A study is designed to investigate

whether there is a difference in response to various treatments in patients

with rheumatoid arthritis. The outcome is patient’s self-reported

effect of treatment. The data are shown below. Is there a statistically

significant difference in the proportions of

patients who show improvement between treatments 1 and 2. Apply the

test at a 5% level of significance.

1.Critical value:

2.Computed statistic:

3.Based on comparing the computed

statistics to the critical value which of the following is (are) true?

a. There is significant evidence, alpha=0.05, to show that there is a

difference in the proportions of patients

who show improvement between treatments 1 and 2.

b.There is not significant evidence, alpha=0.05, to show that there is a

difference in the proportions of

patients who show improvement between treatments 1 and 2.

c. There is significant evidence, alpha=0.05, to show that

there is a no difference in the proportions of

patients who show improvement between treatments 1 and 2.

d. a and c.

Symptoms

Worsened

No

Effect

Symptoms

Improved

Total

Treatment 1

22

14

14

50

Treatment 2

14

15

21

50

·

Question 6

The following data were collected

in a clinical trial to compare a new drug to a placebo for its effectiveness

in lowering total serum cholesterol. Generate a 95% confidence interval

for theproportion of all patients with total

cholesterol < 200.
1.Upper limit of CI:
2.Lower limit of CI:
3.How many patients would be
required to ensure that a 95% confidence interval has a margin of error not
exceeding 5%? n= ____314_____
New
Drug
(n=75)
Placebo
(n=75)
Total
Sample
(n=150)
Mean (SD) Total Serum
Cholesterol
185.0
(24.5)
204.3
(21.8)
194.7
(23.2)
% Patients with Total
Cholesterol < 200
78.0%
65.0%
71.5%
·
Question 7
Peak expiratory flow (PEF) is a
measure of a patient’s ability to expel air from the lungs. Patients
with asthma or other respiratory conditions often have restricted PEF.
The mean PEF for children free of asthma is 306. An investigator
wants to test whether children with chronic bronchitis have restricted PEF.
A sample of 40 children with chronic bronchitis are studied and their
mean PEF is 279 with a standard deviation of 71. Is there statistical
evidence of a lower mean PEF in children with chronic bronchitis? Apply
the appropriate test at alpha=0.05.
1.Critical z value:
2.Computed
z:
3. Based on comparing the critical
z value to the computed z value which of the following is (are) true?
a.
There is statistically significant evidence at alpha=0.05 to show a lower
mean PEF in children with chronic bronchitis?
b. There is not
statistically significant evidence at alpha=0.05 to show a lower mean
PEF in children with chronic bronchitis?
c. There are not enough data
points to reach a conclusion.
d. b and c.
·
Question 8
Average adult Americans are about
one inch taller, but nearly a whopping 25 pounds heavier than they were in
1960, according to a new report from the Centers for Disease Control and
Prevention (CDC). The bad news, says CDC is that average BMI (body mass
index, a weight-for-height formula used to measure obesity) has increased

among adults from approximately 25 in 1960 to 28 in 2002.” Boston is

considered one of America’s healthiest cities – is the weight gain since 1960

similar in Boston? A sample of n=25 adults suggested a mean increase of

17 pounds with a standard deviation of 8.6 pounds. Is Boston

statistically significantly different in terms of weight gain since 1960?

Apply the appropriate test at a 5% level of significance.

1.Critical t value: +/-

2.Computed statistic:

3.Based on comparing the computed

statistic to the critical value which of the following is (are) true?

a.

There is significant evidence, alpha=0.05, that the BMI for Boston residents

is significantly different than 25.

b. There is not significant

evidence, alpha=0.05, that the BMI for Boston residents is significantly

different than 25.

c. Statistically speaking the

difference between the BMI for Boston residents and a BMI of 25 . is 0.

d. b and c.

·

Question 9

The following table was presented

in an article summarizing a study to compare a new drug to a standard drug

and to a placebo.

1.Which, if any, baseline characteristics are

significantly different (at the 0.05 level of significance)

between treatment groups?

a. Disease Stage

b. Annual Income

c. % with Insurance

d. Age

e.

a and c

f. b and d

Characteristic*

New

Drug

Standard

Drug

Placebo

p

Age, years

45.2

(4.8)

44.9

(5.1)

42.8

(4.3)

0.5746

% Female

51%

55%

57%

0.1635

Annual Income, $000s

59.5

(14.3)

63.8

(16.9)

58.2

(13.6)

0.4635

% with Insurance

87%

65%

82%

0.0352

Disease Stage

0.0261

Stage I

35%

18%

33%

Stage II

42%

37%

47%

Stage III

23%

51%

20%

*Table entries and Mean (SD) or %

·

Question 10

A randomized controlled trial is

run to evaluate the effectiveness of a new drug for asthma in children. A

total of 250 children are randomized to either the new drug or placebo (125

per group). There are 63 boys assigned to the new drug group and 58

boys assigned to the placebo. Is there a statistically significant

difference in the proportions of

boys assigned to the treatments? Apply the appropriate test at a 5%

level of significance.

1. Critical value =

2. Computed statistics =

3. Based on comparing the computed statistic to the critical

value which of the following is (are) true?

a.

There

is significant evidence, alpha=0.05, that there is a difference in the proportions of boys assigned to the

treatments.

b.

There

is not significant evidence, alpha=0.05, that there is a difference in

the proportions of boys assigned to the

treatments.

c.

Statistically

speaking the difference in the proportions of

boys assigned to the treatments is 0.

d. b

and c.

·

Question 11

An investigator conducts a study

to investigate whether there is a difference in mean PEF in children with

chronic bronchitis as compared to those without. Data on PEF are

collected and summarized below. Based on the data, is there statistical

evidence of a lower mean PEF in children with chronic bronchitis as compared to

those without? Apply the two sample t test at alpha=0.05.

1.Z 95% Confidence Interval:

2.Upper Limit 95% CI:

3.Lower Limit 95% CI:

4. Based

on comparing the critical the upper and lower limits of the confidence

interval for the mean PEF for children with No Chronic Bronchitis to the mean

PEF for children With Bronchitis which of the following is (are) true. (4 points)

a. There is statistical evidence

of a lower mean PEF in children with chronic bronchitis as compared to those

without.

b. There is not statistical

evidence of a lower mean PEF in children with chronic bronchitis as compared

to those without.

c. The confidence interval

contains the mean PEF for the No Chronic Bronchitis group.

d. a and c.

Group

Number

of Children

Mean

PEF

Std

Dev PEF

Chronic Bronchitis

25

281

68

No Chronic Bronchitis

25

319

74

·

Question 12

The table below summarizes

baseline characteristics on patients participating in a clinical trial.

1.Which, if any, baseline

characteristics are significantly different (at the 0.05 level of

significance) between treatment groups? (10 points)

a. Age

b. Total Cholesterol

c. Diabetes

d. % Female

e. a and b

f.

c and d

Characteristic

Placebo

(n=125)

Experimental

(n=125)

P

Mean (+SD) Age

54

+ 4.5

53

+ 4.9

0.7856

% Female

39%

52%

0.0289

% Less than High School

Education

24%

22%

0.0986

% Completing High School

37%

36%

% Completing Some College

39%

42%

Mean (+SD) Systolic

Blood Pressure

136

+ 13.8

134

+ 12.4

0.4736

Mean (+SD) Total

Cholesterol

214

+ 24.9

210

+ 23.1

0.8954

% Current Smokers

17%

15%

0.5741

% with Diabetes

8%

3%

0.0438

·

Question 13

A small pilot study is conducted

to investigate the effect of a nutritional supplement on total body weight.

Six participants agree to take the nutritional supplement. To

assess its effect on body weight, weights are measured before starting the

supplementation and then after 6 weeks. The data are shown below.

Is there a significant increase in body weight following supplementation?

Use a paired t-test at a 5% level of significance.

1.df=__5___

2.Critical value:As this is a left tailed test so critical

value = -t(0.05,df = 5) = -2.015; From t-table

3.Computed statistic:As we can see that this is a paired sample

test so we need to find out the difference and the mean and standard

deviation of the differences. The differences are -2, -3, -4, 5, 1 and -1

which is giving mean = -0.6667 and sample standard deviation = 3.2660.

So test statistic = = -0.50

4.Based on comparing the computed

statistic to the critical value which of the following is (are) true?

a. There is significant evidence,

alpha=0.05, to show that body weight increased following supplementation?

b.

There is not significant evidence, alpha=0.05, to show that body weight

increased following supplementation?

c. Statistically speaking the

difference in initial weights and weights after 6 weeks is 0.

d. b and c.

Subject

Initial

Weight

Weight

after 6 Weeks

1

155

157

2

142

145

3

176

180

4

180

175

5

210

209

6

125

126

·

Question 14

The graph below shows what kind of

relationship between the independent and dependent variables:

The

graph shows a positive relationship between the independent and dependent

variables.

·

Question 15 (IGNORE THIS

QUESTION)

Which of the following is NOT true

concerning scatterplots?

D. The unit of measure on the X and Y axis must be the same.

·

Question 16

Examine the above graphs below and

answer the following questions.

1.Which of the above graphs

indicates a negative relationship between the

graphed variables?

(Include all that are negative)

D, E and F

2.On which axis is the dependent variable

graphed?

3.Which of the above graphs

indicated the highest correlation?

·

Question 17

The following data were collected

in a study relating hypertensive status measured at baseline to incident

stroke over 5 years.

1.Compute the cumulative incidence

of stroke in the study.

Cumulative Incidence =

2.Compute the cumulative incidence

of stroke in patients classified as hypertensive at baseline.

Cumulative Incidence Hypertensive

=

3.Compute the cumulative incidence

of stroke in patients free of hypertension at baseline.

Cumulative Incidence Not

Hypertensive =

4.Compute the risk difference of

stroke in patients with hypertension as compared to patients free of

hypertension.

Risk Difference =

5.Compute the relative risk of

stroke in patients with hypertension as compared to patients free of

hypertension.

Relative Risk =

6.Compute the population

attributable risk of stroke due to hypertension.

PAR =

·

Question 18

The survival curve below depicts

survival times and rates for a particular cancer diagnosed at various stages

of progression.

1.At what time (to the nearest year)

does 12 year survival appear certain for Stages II cancer?

2.For Stage I cancer what is the

minimum survival time (to the nearest year)? 1 year

3.What is the median survival time

for Stage IV cancer (to the nearest year)? 1

year

·

Question 19

In a 10 year study of CAD some

patients were not followed for a total of 10 years. Some suffered

events (i.e., developed coronary artery disease during the course of

follow-up) while others dropped out of the study. The following table

displays the total number of person-years of follow-up in each group.

1.Compute the incidence rate of

coronary artery disease in patients receiving the new medication.

Incidence Rate New Medication = per 1,000

person years.

2.Compute the incidence rate of

coronary artery disease in patients receiving placebo.

Incidence Rate Placebo = per 1,000 person years.

·

Question 20

A small cohort study is conducted

in 13 patients with an aggressive cellular disorder linked to cancer.

The clinical courses of the patients are depicted graphically below.

1.Compute the prevalence of cancer

at 12 months.

Prevalence =

2.Compute the cumulative incidence

of cancer at 12 months.

Cumulative Incidence 12 Months =

3.Compute the incidence rate (per

month) of cancer.

Incidence Rate =

4.Compute the incidence rate (per

month) of death.

Incidence Rate =

.

## Recent Comments