Chapter I
Statistics, Data, and Statistical
Thinking
Exercises
Understanding the Principles
• The difference between descriptive and
inferential statistics.
• List and define the five elements of an
inferential statistical analysis
Population; variables; sample;
inference; measure of reliability
List the four major methods of collecting
data, and explain their differences.
Explain how population and variables
differ
What is a representative sample? What is
its value?
Define statistical thinking
Colleges and universities are requiring an
increasing amount of information about
applicants before making acceptance and
financial aid decisions. Classify each of the
following types of data required on a
college application as quantitative or
qualitative.
a.
b.
c.
d.
e.
f.
High School GPA
High school class rank
Applicant’s score on the SAT or ACT
Gender of applicant
Parent’s income
Age of applicant
Extinct birds. Biologists at the University of California (Riverside) are
studying the patterns of extinction in the New Zealand bird population.
(Evolutionary Ecology Research, July 2003.) At the time of the Maori
colonization of New Zealand (prior to European contact), the following
variables were measured for each bird species:
a.
b.
c.
d.
e.
f.
g.
h.
Flight capability (volant or flightless)
Type of habitat (aquatic, ground terrestrial, or aerial terrestrial)
Nesting site (ground, cavity within ground, tree, cavity above ground)
Nest density (high or low)
Diet (fish, vertebrates, vegetables, or invertebrates)
Body mass (grams)
Egg length (milimeters)
Extinct status (extinct, absent from island, present)
Identify each variable as quantitative of qualitative.
Herbal medicines. The American Association of Nurse Anesthetists Journal
(Feb. 2000) published the results of a study on the use of herbal
medicines before surgery. Of 500 surgical patients randomly selected for
the study, 51% used herbal or alternative medicines (e.g. garlic, gingkgo,
kava, fish oil) against their doctor’s advice prior to surgery.
a. Do the 500 surgical patients represent a population or a sample?
Explain.
b. If your answer was «sample» in part a. is the sample representative of
the population? If you answered «population» in part a, explain how
to obtain a representative sample from a population.
c. For each patient, what variable is measured? Are the data collected
quantitative or qualitative?
Poll on alien spacecraft.
«Have you ever seen anything that you believe was a spacecraft from another
planet» This was the question put to 1500 American adults in a national poll
conducted by ABC News and The Washington Post. The pollsters used random
digit telephone dialing to connect adult American until 1500 responded. Then
percent (i.e., 150) of the respondents answered that they had, in fact, seen an
alien spacecraft. No information was provided on how many adults were called
and, for one reason or another, did not answer the question.
a. Identify the data collection method.
b. Identify the target population.
c. Comment on the validity of the survey results.