Need two assignments complete for Biostatistics

Problems retrieved from

Gerstman

, B. B. (2015).

Basic biostatistics: Statistics for public health practice

(2nd ed.). Burlington,

MA: Jones and Bartlett. ISBN: 978

-

1

-

284

-

03601

-

5

IHP 525 Module Two Problem Set

1.

Five

-

City Project.

The Stanford Five

-

City Project is a comprehensive community health

education study of five moderately sized Northern California towns. Multiple

-

risk factor

intervention strategies were randomly applied to two of the communities. The other three cities

ser

ved as controls. Outline the design of this study in schematic form.

2.

Employee counseling.

An employer offers its employees a program that will provide up to four

free psychological counseling sessions per calendar year. To evaluate satisfaction with this

service, the counseling office mails questionnaires to every 10th employee who used the benefit

in the prior year. There were 1000 employees who used the benefit. Therefore, 100 surveys

were sent out. However, only 25 of the potential respondents complete

d and returned their

questionnaire.

a)

Describe the population for the study.

b)

Describe the sample.

c)

What concern is raised by the fact that only 25 of the 100 questionnaires were

completed and returned?

3.

Air samples.

An environmental study looked at suspended particulate matter in air samples

(µg/m3) at two different sites. Data are listed here. Construct

a stemplot of for each site (here is

where s

ide

-

by

-

side ste

mplots

would be helpful but not required)

and then comp

are the

distribution of suspended particulate matter between the two sites (remember to mention

center and spread). No calculations necessary.

Site 1: 68

22

36

32

42

24

28

38

Site 2: 36

38

39

40

36

34

33

32

4.

What would you report?

What is an

appropr

iate measure of central location for data

that are

really

skewed?

What is an appropriate measure of spread for data that are really skewed?

5.

Melanoma treatment.

A study by Morgan and coworkers used genetically modified white blood

cells to treat patients

with melanoma who had not responded to standard treatments. In

patients in whom the cells were cultured ex vivo for an extended period of time (cohort 1), the

cell doubling times were {8.7, 11.9, 10.0} days. In a second group of patients in whom the cells

were cultured for a shorter period of time (cohort 2), the cell doubling times were {1.4, 1.0, 1.3,

1.0, 1.3, 2.0, 0.6, 0.8, 0.7, 0.9, 1.9} days. In a third group of patients (cohort 3), actively dividing

cells were generated by performing a second rapid

expansion via active cell transfer. Cell

doubling times for cohort 3 were {0.9, 3.3, 1.2, 1.1} days.

a)

Create side

-

by

-

side boxplots of these data

(so each boxplot uses the same y

-

axis)

.

b)

In addition, calculate the mean and standard deviations within each

group. Comment on

your findings.

Problems retrieved from Gerstman, B. B. (2015). Basic biostatistics: Statistics for public health practice (2nd ed.). Burlington,

MA: Jones and Bartlett. ISBN: 978-1-284-03601-5

IHP 525 Module Two Problem Set

1. Five-City Project. The Stanford Five-City Project is a comprehensive community health

education study of five moderately sized Northern California towns. Multiple-risk factor

intervention strategies were randomly applied to two of the communities. The other three cities

served as controls. Outline the design of this study in schematic form.

2. Employee counseling. An employer offers its employees a program that will provide up to four

free psychological counseling sessions per calendar year. To evaluate satisfaction with this

service, the counseling office mails questionnaires to every 10th employee who used the benefit

in the prior year. There were 1000 employees who used the benefit. Therefore, 100 surveys

were sent out. However, only 25 of the potential respondents completed and returned their

questionnaire.

a) Describe the population for the study.

b) Describe the sample.

c) What concern is raised by the fact that only 25 of the 100 questionnaires were

completed and returned?

3. Air samples. An environmental study looked at suspended particulate matter in air samples

(µg/m3) at two different sites. Data are listed here. Construct a stemplot of for each site (here is

where side-by-side stemplots would be helpful but not required) and then compare the

distribution of suspended particulate matter between the two sites (remember to mention

center and spread). No calculations necessary.

Site 1: 68 22 36 32 42 24 28 38

Site 2: 36 38 39 40 36 34 33 32

4. What would you report? What is an appropriate measure of central location for data that are

really skewed? What is an appropriate measure of spread for data that are really skewed?

5. Melanoma treatment. A study by Morgan and coworkers used genetically modified white blood

cells to treat patients with melanoma who had not responded to standard treatments. In

patients in whom the cells were cultured ex vivo for an extended period of time (cohort 1), the

cell doubling times were {8.7, 11.9, 10.0} days. In a second group of patients in whom the cells

were cultured for a shorter period of time (cohort 2), the cell doubling times were {1.4, 1.0, 1.3,

1.0, 1.3, 2.0, 0.6, 0.8, 0.7, 0.9, 1.9} days. In a third group of patients (cohort 3), actively dividing

cells were generated by performing a second rapid expansion via active cell transfer. Cell

doubling times for cohort 3 were {0.9, 3.3, 1.2, 1.1} days.

a) Create side-by-side boxplots of these data (so each boxplot uses the same y-axis).

b) In addition, calculate the mean and standard deviations within each group. Comment on

your findings.