Question

in 1994, science magazine compared vegetarians and nonvegetarians and reported that

vegetarians had a 28% lower death rate from heart attacks and a 39% lower death rate from

cancer

1.   What kind of study is this?

a.   Matched-

pairs

b.   Observational study

c.   Completely randomized design

d.   Randomized block design

2.   What is/are the response variable(s)?

a.   The magazine issuing the survey

b.   The type of diet (vegetarian or nonvegetarian)

c.   The year the survey was conducted

d.   Death rates from heart attacks and cancer

3.   Researchers want to know if the type of music students listen to affects their ability to

retain information. Each student read a chapter from a history textbook while listening to

pop music. Then, the same group of students read a different chapter while listening to

classical music. A test on each chapter was given, and the scores are compared. What

kind of study is this?

a.   Matched-

pairs

b.   Observational study

c.   Completely randomized design

d.   Randomized block design

4.   Volunteers with high blood pressure were split into two groups by age, with individuals

under 50 placed in one group and individuals over 50 in the other group. Within each

age group, the volunteers were randomly assigned a meditation class or nothing at all. After 4 months, their blood pressures were measured again to see if there was improvement. What kind of study is this?

a.   Matched-

pairs

b.   Observational study

c.   Completely randomized design

d.   Randomized block design

5.   60 men with receding hairlines volunteer for an experimental medication for restoring

hair. 30 men are randomly assigned to the treatment, and the other 30 are assigned a

placebo. What kind of study is this?

a.   Matched-

pairs

b.   Observational study

c.   Completely r

andomized design

d.   Randomized block design

Four astronauts had their lymphocyte count measured 1 day before takeoff, and again when

they returned to earth.

6.   What kind of study is this?

a.   Matched-

pairs

b.   Observational study

c.   Completely randomized design

d.   Randomized block design

7.   In the previous scenario, what is the explanatory variable?

a.   Lymphocyte count

b.   Days after takeoff

c.   Exposure to space

d.   The astronaut being studied

8.   225 patients with irritated skin were randomly divided into 3 groups. Group 1 received a

salve with a medicinal concentration of 5%. Group 2 received a concentration of 1%.

Group 3 received a placebo. What kind of study is this?

a.   Matched-

pairs

b.   Observational study

c.   Completely randomized design

d.   Randomized block design

9.   A comedian is testing a

new joke before going on tour. She is trying to determine the

best of 3 different punchlines. First she splits her sample by putting all people aged 21-

40 in one group and all people aged 41-60 in a second group. Within each groups, she

randomly assigns them to subgroups, each of which will hear a different punchline.

What kind of study is this?

a.   Matched-

pairs

b.   Observational study

c.   Completely randomized design

d.   Randomized block design

Answer 1

1. b) Observational study

(The subjects are not controlled by the experimenter in this study and hence, it is an observational study)

2. d) Death rates from heart attacks and cancer

(The variable in which changes occur corresponding to change in the explanatory variable is the response variable)

3. a) Matched-pairs

(different treatments are given to similar subjects and results are compared)

4. d) Randomized block design

(The subjects are divided into blocks, based on their age)

5. c) Completely randomized design

(The subjects are randomly assigned to placebo and treatment)

6. b) Observational study

7. c) Exposure to space

(the change in the lymphocyte count is explained by the exposure to space and hence, it is the explanatory variable)

8. c) Completely randomized design

9. d) Randomized block design