For a more thorough review, refer to these concepts:

- Quantitative Versus Qualitative Data for AP Statistics
- Descriptive Versus Inferential Statistics for AP Statistics
- Collecting Data: Surveys, Experiments, Observational Studies for AP Statistics

### Rapid Review

*Answer:* False. The data are measured on a numerical, not categorical, scale.

*Answer:* True. The data are countable (e.g., Leroy has owned 8 cars).

*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.")

*Answer:* A numerical outcome of an experiment or random phenomenon.

*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.

*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.

*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.

*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.

*Answer:* Statistics: b, e, f

Parameters: a, c, d

- True or False: A study is done in which the data collected are the number of cars a person has owned in his or her lifetime. This is an example of
*qualitative*data. - True or False: The data in the study of question number 1 are
*discrete*. - What are the names given to values that describe samples and values that describe
*populations*? - What is a
*random variable*? - Why do we need to
*sample*? - Why do we need to take care with data collection?
- Which of the following are examples of
*qualitative*data?- The airline on which a person chooses to book a flight
- The average number of women in chapters of the Gamma Goo sorority
- The race (African American, Asian, Hispanic, Pacific Islander, White) of survey respondents
- The closing Dow Jones average on 50 consecutive market days
- The number of people earning each possible grade on a statistics test
- The scores on a given examination

- Which of the following are
*discrete*and which are*continuous*?- The number of jelly beans in a jar
- The ages of a group of students
- The humidity in Atlanta
- The number of ways to select a committee of three from a group of ten
- The number of people who watched the Super Bowl in 2002
- The lengths of fish caught on a sport fishing trip

- Which of the following are
*statistics*and which are*parameters*?- The proportion of all voters who will vote Democrat in the next election
- The proportion of voters in a Gallup Poll who say they will vote Democrat in the next election
- The mean score of the home team in all NFL games in 1999
- The proportion of Asian students attending high school in the state of California
- The mean difference score between a randomly selected class taught statistics by a new method and another class taught by an old method
- The speed of a car

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