STAT 1350, Quiz #4, Summer 2014Name _______________________________________

1.
Confounding often defeats attempts to show that one variable causes changes in another variable. Confounding means that
A)
this was an observational study, so cause and effect conclusions are not possible.
B)
the effects of several variables are mixed up, so we cannot say which is causing the response.
C)
we don\'t know which is the response variable and which is the explanatory variable.
D)
we would get widely varied results if we repeated the study many times.

Ans: B

2.
Which of the following are the three principles of experimental design?
A)
Confound, Randomize, Small Samples
B)
Confound, Randomize, Large Samples
C)
Control, Randomize, Small Samples
D)
Control, Randomize, Large Samples

Ans: D

3.
The most important advantage of experiments over observational studies is
A)
experiments are usually easier to carry out.
B)
a well-designed experiment can give good evidence that the treatments actually cause the response.
C)
an experiment can compare two or more groups.
D)
we can use randomization to avoid bias in designing an experiment.
E)
we can study the relationship between two or more explanatory variables.

Ans: B

4.
A psychologist recently said that, "For relatively mild medical problems, the placebo effect will produce positive results in roughly two-thirds of patients." The placebo effect is
A)
the bias due to voluntary response in a sample.
B)
the effect of a dummy treatment on a patient.
C)
a violation of comparative experimentation.
D)
the effect of confounding in an observational study.

Ans: B

5.
To control for the power of suggestion when a subject takes an experimental drug, use
A)
a placebo.
C)
double blinding.
B)
blocking.
D)
probability sampling.

Ans: A

6.
The reason that block designs are sometimes used in experimentation is to
A)
prevent the placebo effect.
B)
allow double-blinding.
C)
reduce sampling variability.
D)
eliminate sampling variability.

Ans: C

7.
We say that the design of a study is biased if which of the following is true?
A)
We suspect racial or sexual prejudice.
B)
The study assigns subjects at random to a placebo.
C)
The study systematically favors certain outcomes.
D)
The study fails to use blocking.
E)
The study is double-blind.

Ans: C

8.
The basic ethical requirements for any study of human subjects are
A)
comparison, randomization, and replication.
B)
approval by a review board, informed consent, and confidentiality of data.
C)
subjects are anonymous, subjects are randomly chosen, and subjects cannot be harmed.
D)
data production, data analysis, and inference.

Ans: B

9.
The student-run newspaper asks students to visit a web page and respond to questions regarding a proposed tuition increase. Only responses to the questions are recorded. Summary statistics based on the survey responses are used in an article published the following week, and no one outside of the newspaper has access to the individual responses. The newspaper\'s survey is considered to be
A)
anonymous.
B)
confidential.
C)
both anonymous and confidential.
D)
neither anonymous nor confidential.

Ans: C

10.
A psychologist says that scores on a test for "authoritarian personality" can\'t be trusted because the test counts religious belief as authoritarian. The psychologist is attacking the test\'s

A) validity. B) reliability. C) margin of error. D) confidence level.

Ans: A

11.
During a visit to the doctor, you are weighed on a very accurate scale. You are weighed five times and the five readings are essentially the same. When being weighed, you are wearing all of your clothes and a pair of hiking boots. As a measure of your weight without clothes, the reading on the scale is
A)
unbiased and reliable.
D)
biased and unreliable.
B)
unbiased and unreliable.
E)
biased and reliable.
C)
95% accurate.

Ans: E

12-13. A student\'s research shows that there were more suicides in 2010 than there were in 1910. He concludes that people were less likely to commit suicide in 1910 than in 2010.

12.
Why is it not valid to use these two numbers to compare suicides in these two years?

A) People were happier in 2010 than they were in 1910.

B) The numbers were compiled by a student instead of by a professional researcher.

C) The U.S. population increased substantially from 1910 to 2010.

D) One shouldn\'t compare years that are so far apart.

Ans: C

13.
What would be a more appropriate or valid measure for this comparison?

A) Compare the number of suicides in 1900 and 2000.

B) Compare the suicide rates (percentages) for 1910 and 2010.

C) Compare the number of suicides in those years, grouped by region.

D) Compare the number of people who don\'t commit suicide for 1910 and 2010.

Ans: B