Answer: False. The data are measured on a numerical, not categorical, scale.
True or False: The data in the study of question number 1 are discrete .
Answer: True. The data are countable (e.g., Leroy has owned 8 cars).
What are the names given to values that describe samples and values that describe populations ?
Answer: Values that describe samples are called statistics , and values that describe populations are
called parameters . (A mnemonic for remembering this is that both statistic and sample begin with
“s,” and both parameter and population begin with “p.”)
What is a random variable ?
Answer: A numerical outcome of an experiment or random phenomenon.
Why do we need to sample ?
Answer: Because it is usually too difficult or too expensive to observe every member of the
population. Our purpose is to make inferences about the unknown, and probably unknowable,
parameters of a population.
Why do we need to take care with data collection?
Answer: In order to avoid bias. It makes no sense to try to predict the outcome of the presidential
election if we survey only Republicans.
Which of the following are examples of qualitative data?
(a) The airline on which a person chooses to book a flight
(b) The average number of women in chapters of the Gamma Goo sorority
(c) The race (African American, Asian, Hispanic, Pacific Islander, White) of survey respondents
(d) The closing Dow Jones average on 50 consecutive market days
(e) The number of people earning each possible grade on a statistics test
(f) The scores on a given examination
Answer: a, c, and e are qualitative. f could be either depending on how the data are reported:
qualitative if letter grades were given, quantitative if number scores were given.
Which of the following are discrete and which are continuous ?
(a) The number of jelly beans in a jar
(b) The ages of a group of students
(c) The humidity in Atlanta
(d) The number of ways to select a committee of three from a group of ten
(e) The number of people who watched the Super Bowl in 2002
(f) The lengths of fish caught on a sport fishing trip
Answer: Discrete: a, d, e
Continuous: b, c, f
Note that (b) could be considered discrete if by age we mean the integer part of the age—a person is
considered to be 17, for example, regardless of where that person is after his/her 17th birthday and
before his/her 18th birthday.
Which of the following are statistics and which are parameters?
