Chapter 1234

Chapter1234
Student’s Name
Institution Affiliation

1.8. Indicating whether the study is an experiment or observation
Solutions
a. Observational
b. Observational
c. Experiment; variables are Sexual codes of primitive tribes(independent) and behavior
toward neighboring tribes(confounding variables)
d. Observational
e. Experiment; Variables are Reading comprehension scores(confounding variable) and
Number of months of formal education(independent variable)
f. Experiment; Variables are Graduate Record Exam(GRE) score(Confounding variable)
and cramming(independent variable)
g. Experiment; Variables are Attractive Score by panel of peer(confounding variable) and
Score on paper- and-pencil(independent variable)
h. Experiment; male attitude toward spending by federal government(independent variable)
and female attitude toward federal government spending(confounding variable)
i. Observational
1.9. Experiments and observational studies
a. what make studies to be experiment
Presence of control group
b. Confounding variables controlled by breastfeeding
 Adult intelligence
 Cognitive(IQ) development

2.14. Number of different residences occupied by graduating seniors during their college career
a. Frequency distribution
Number of Residences Frequency
1 1
2 6
3 8
4 5
5 1
6 1
7 1
9 1
Total 24
b. Shape of the distribution
The distribution is not bell shape, instead it’s data skewed to the left
2.17. Difference between two distributions; one reflection of the ages of all residents of small
town and the other reflecting the age of all U.S. residents.
a. Converting frequencies to %
AGE SMALL
TOWNf
SMALL TOWN
PERCENTAGE
U.S.POPULATION
(2010) (%)
65-above 105 21% 13%
60-64 53 11% 5%
55-59 45 9% 6%
50-54 40 8% 7%
45-49 44 9% 7%
40-44 38 8% 7%
35-39 31 6% 7%
30-34 27 5% 6%
25-29 25 5% 7%
20-24 20 4% 7%
15-19 20 4% 7%
10-14 19 4% 7%
5-9 17 3% 7%
0-4 16 3% 7%
500 100% 100%