Author: admin

For each of the following cases, indicate
which statistic should be used—mean,
standard deviation, z score, or Pearson r.
a. We want to know how spread out or
heterogeneous the scores of a class
are.
b. We want to determine how Joe’s score
compares with the scores of the rest of
the class.
c. We want to know how well the class as a
whole did on an examination.
d. We want to predict the future achievement of students
from their IQ.

Interpret the following: “On the College Board exam (μ=
500, σ= 100), the mean of this year’s Central High School seniors was 490,
and the standard deviation was 110. The correlation between the exam scores and
high school grade point average was +.40.”

1. Interpret the following: “Parents of Central High
students were asked to rank 10 problems from 10 = most serious to 1 = less
serious. The median for the problem ‘physical safety’ was 5.21.”
2. Smith and Glass’s ∆ and Cohen’s d are two ways of
defi ning what?
3. Defi ne effect size, and tell how it is used.

You have been asked to determine whether teachers in the
Springfi eld School District favor the “year-round school” concept. Because the
district is rather large, you are asked to contact only 500 teachers. Determine
the number you would choose from each of the following levels to draw a
proportional stratifi ed random sample:

A national magazine has 1 million subscribers. The editorial
staff wants to know
which aspects of the magazine are liked
and which are not. The staff decides that
a personal interview is the best method to
obtain the information. For practical and
economic reasons, only 500 people in fi ve
cities will be surveyed. In this situation,
identify the following:
a. The population
b. The sample

Investigators wish to study the question,
“Do blondes have more fun?”
a. What is the null hypothesis in this
question?
b. What would be a Type I error in this case?
c. What would be a Type II error in this case?
d. If one investigator uses a .05 level of
signifi cance in investigating this question
and another investigator uses a .001
level of signifi cance, which would be
more likely to make a Type I error?
e. If one investigator uses a .05 level of
signifi cance in investigating this question and another
investigator uses a .001
level of signifi cance, which would be
more likely to make a Type II error?

Inferential statistics enable researchers to
do which of the following?
a. Reach infallible conclusions
b. Reach reasonable conclusions with
incomplete information
c. Add an aura of legitimacy to what is
really sheer guesswork

Which of the following statements
describes the role of the null hypothesis in
research?
a. It enables researchers to determine
the probability of an event occurring
through chance alone when there is no
real relationship between variables.
b. It enables researchers to prove there is a
real relationship between variables.
c. It enables researchers to prove there is
no real relationship between variables.

A Type II error occurs when a researcher
does which of the following?
a. Rejects a false null hypothesis
b. Rejects a true null hypothesis
c. Has already made a Type I error
d. Retains a false null hypothesis
e. Retains a true null hypothesis