Complete the following exercises from
“Review Questions” located at the end of each chapter and put them
into a Word document to be submitted as directed by the instructor.
Chapter 1, numbers 1.8 and 1.9
Chapter 2, numbers 2.14, 2.17, and 2.18
Chapter 3, numbers 3.13, 3.14, 3.18, and
3.19
Chapter 4, numbers 4.9, 4.14, 4.17, and
4.19
Show all relevant work; use the equation
editor in Microsoft Word when necessary
Chapter 1
1.8 Indicate whether each of the following
studies is an experiment or an
observational study. If it is an
experiment, identify the independent variable
and note any possible confounding
variables.
(a) A psychologist uses chimpanzees to test
the notion that more crowded
living conditions trigger aggressive
behavior. Chimps are placed, according
to an impartial assignment rule, in cages
with either one, several, or
many other chimps. Subsequently, during a
standard observation period,
each chimp is assigned a score based on its
aggressive behavior toward a
chimp like stuffed doll.
(b) An investigator wishes to test whether,
when compared with recognized,
professional scientists, recognized,
professional artists tend to be born
under different astrological signs.
(c) To determine whether there is a
relationship between the sexual codes of
primitive tribes and their behavior toward
neighboring tribes, an anthropologist
consults available records, classifying
each tribe on the basis of
its sexual codes (permissive or repressive)
and its behavior toward neighboring
tribes (friendly or hostile).
(d) In a study of group problem solving, an
investigator assigns college students
to groups of two, three, or four students
and measures the amount
of time required by each group to solve a
complex puzzle.
(e) A school psychologist wishes to determine
whether reading comprehension
scores are related to the number of months
of formal education, as reported
on school transcripts, for a group of
12-year-old migrant children
1.9 Recent studies, as summarized, for
example, in E. Mortensen et al. (2002).
The association between duration of
breastfeeding and adult intelligence.
Journal of the American Medical Association
, 287 , 2365–2371, suggest
that breast-feeding of infants may increase
their subsequent cognitive
((IQ) development. Both experiments and
observational studies are cited.
(a ) What determines whether some of these
studies are experiments?
(b) Name at least two potential confounding
variables controlled by breastfeeding
experiments.
Chapter 2
REVIEW QUESTIONS 53
REVIEW QUESTIONS
2.14 (a) Construct a frequency distribution
for the number of difference residences
occupied by graduating seniors during their
college career,
namely
1, 4, 2, 3, 3, 1, 6, 7, 4, 3, 3, 9, 2, 4,
2, 2, 3, 2, 3, 4, 4, 2, 3, 3, 5
(b) What is the shape of this distribution
*2.17 Are there any conspicuous differences
between the two distributions in
the following table (one reflecting the
ages of all residents of a small town
and the other reflecting the ages of all
U.S. residents)?
(a) To help make the desired comparison,
convert the frequencies ( f ) for the
small town to percentages.
(b) Describe any seemingly conspicuous
differences between the two distributions.
TWO AGE DISTRIBUTIONS
SMALL TOWN U.S. POPULATION (2010)
AGE f (%)
65–above 105 13
60–64 53 5
55–59 45 6
50–54 40 7
45–49 44 7
40–44 38 7
35–39 31 7
30–34 27 6
25–29 25 7
20–24 20 7
15–19 20 7
10–14 19 7
5–9 17 7
0–4 16 7
Total 500 100%
NOTE: The top class (65–above) has no upper
boundary. Although less
preferred, as discussed previously, this
type of open-ended class is
employed as a space-saving device when, as
in the Statistical Abstract of
the United States, many different tables
must be listed.
Source: 2012 Statistical Abstract of the
United States.
(c) Using just one graph, construct
frequency polygons for the two relative
frequency distributions.
NOTE: When segmenting the horizontal axis,
assign the same width to the open ended
interval (65–above) as to any other class
interval. (This tactic
causes some distortion at the upper end of
the histogram, since one class
interval is doing the work of several.
Nothing is free, including the convenience
of open-ended intervals.)
Answers on Page 501.
2.18 The following table shows
distributions of bachelor’s degrees earned in
2005–2006 for selected fields of study by
all male graduates and by all
female graduates.
(a) How many female psychology majors
graduated in 2005–2006?
(b) Since the total numbers of male and
female graduates are fairly different—
504,600 and 676,000—it is helpful to
convert fi rst to relative frequencies
before making comparisons between male and
female graduates. Then,
inspect these relative frequencies and note
what appear to be the most
conspicuous differences between male and
female graduates.
(c) Would it be meaningful to cumulate the
frequencies in either of these
frequency distributions?
(d) Using just one graph, construct bar
graphs for all male graduates and for
all female graduates. Hint: Alternate
shaded and unshaded bars for males
and females, respectively.
BACHELOR’S DEGREES EARNED IN 2005–2006
BY SELECTED FIELD OF STUDY AND GENDER
(IN THOUSANDS)
MAJOR FIELD OF STUDY MALES FEMALES
Business 159.7 158.4
Social sciences 80.8 80.7
Education 22.4 84.8
Health sciences 12.9 79.1
Psychology 19.9 68.3
Engineering 67.0 14.6
Life sciences 26.7 42.5
Fine arts 32.1 51.2
Communications 28.1 48.8
Computer sciences 37.7 9.8
English 17.3 37.8
Total 504.6 676.0
Source: 2007 Digest of Educational
Statistics at http://nces.ed.gov.
Chapter 3
72 DESCRIBING DATA WITH AVERAGES
3.13 Garrison Keillor, host of the radio
program A Prairie Home Companion ,
concludes each story about his mythical
hometown with “That’s the
news from Lake Wobegon, where all the women
are strong, all the men
are good-looking, and all the children are
above average.” In what type
of distribution, if any, would
(a) more than half of the children be above
average?
(b) more than half of the children be below
average?
(c) about equal numbers of children be
above and below average?
(d) all the children be above average?
3.14 The mean serves as the balance point
for any distribution because the
sum of all scores, expressed as positive
and negative distances from the
mean, always equals zero.
(a) Show that the mean possesses this
property for the following set of
scores: 3, 6, 2, 0, 4.
(b) Satisfy yourself that the mean
identifies the only point that possesses
this property. More specifically, select
some other number, preferably a
whole number (for convenience), and then fi
nd the sum of all scores in
Part (a) expressed as positive or negative
distances from the newly
selected number. This sum should not equal zero.
3.18 Given that the mean equals 5, what
must be the value of the one missing
observation from each of the following sets
of observations?
(a) 1, 2, 10
(b) 2, 4, 1, 5, 7, 7
(c) 6, 9, 2, 7, 1, 2
3.19 Indicate whether the following terms
or symbols are associated with the
population mean, the sample mean, or both
means.
(a) N
(b) varies
(c) S
(d) n
(e) constant
(f) subset
Chapter 4
Key Equations
STANDARD DEVIATION FOR SAMPLE
s
SS
df
= = SS
n ?1
where SS X
X
= ? n ( ) ? 2 ?
2
REVIEW QUESTIONS
*4. 9 For each of the following pairs of
distributions, fi rst decide whether their
standard deviations are about the same or
different. If their standard deviations
are different, indicate which distribution
should have the larger
standard deviation. Hint: The distribution
with the more dissimilar set of
scores or individuals should produce the
larger standard deviation regardless
of whether , on average, scores or
individuals in one distribution differ
from those in the other distribution.
(a) SAT scores for all graduating high
school seniors (a 1 ) or all college freshmen
(a 2 )
(b) Ages of patients in a community
hospital (b 1 ) or a children’s hospital (b 2 )
(c) Motor skill reaction times of
professional baseball players (c 1 ) or college
students (c 2 )
(d) GPAs of students at some university as
revealed by a random sample (d 1 )
or a census of the entire student body (d 2
)
(e) Anxiety scores (on a scale from 0 to
50) of a random sample of college
students taken from the senior class (e 1 )
or those who plan to attend an
anxiety-reduction clinic (e 2 )
(f) Annual incomes of recent college
graduates (f 1 ) or of 20-year alumni (f 2 )
Answers on page 503
4.14 (a) Using the computation formula for
the sample sum of squares, verify
that the sample standard deviation, s ,
equals 23.33 lbs for the distribution
of 53 weights in Table 1.1.
(b) Verify that a majority of all weights
fall within one standard deviation of the
mean (169.51) and that a small minority of
all weights deviate more than
two standard deviations from the mean.
4. 17 Why can’t the value of the standard
deviation ever be negative?
4.19 Referring to Review Question 2.18 on
page 55, would you describe the
distribution of majors for all male
graduates as having maximum, intermediate,
or minimum variability?
