Chapter 2

Question 1

Observation

Answer 1

A single member of a collection of items we want to study. Ex. an employee, a car wash. (23)

Question 2

Variable

Answer 2

A characteristic of the subject or individual. Ex. Employee income, cost of car wash. (23)

Question 3

Categorical (qualitative) data

Answer 3

Have values described by words rather than numbers. Ex. Type of car (sedan, coupe, convertible, etc.)

Question 4

Binary variables

Answer 4

Categorical variables with only two values. Ex. Male (0) and female (1)

Question 5

Numerical (quantitative) data

Answer 5

Arise from counting, measuring, or some other mathematical operation. They’re numbers! Two types (discrete and continuous) Ex. Money spent last month.

Question 6

Discrete numerical variable

Answer 6

A variable with a countable number of distinct values. Usually starts with “number of”. Ex. Number of cars sold in the last week.

Question 7

Continuous numerical variable

Answer 7

A variable that CAN HAVE any value within an interval. Ex. Distance, time, speed. Even if speed is rounded to the nearest mph, it’s continuous.

Question 8

Time series data

Answer 8

Occurs when each observation in the sample represents a different equally spaced point in time.

Question 9

Nominal data (level of measurement)

Answer 9

Weakest level of measurement, easiest to recognize. Ex. Which cell phone service provider do you use? 1. AT&T, 2. Verizon, 3. Other. Numbers are irrelevant (can’t calc. average)

Question 10

Ordinal data (level of measurement)

Answer 10

Connote a ranking of data values. Numbers have more of a meaning, but the distance between numbers is irrelevant (Great to good vs. good to ok). Ex. What was your experience at Disneyland? 1. Great, 2. Good, 3. Ok, 4. Bad.

Question 11

Interval data (level of measurement)

Answer 11

Connote a ranking of data and intervals between values are important. Ex. Fahrenheit scale, lbs scale.

Question 12

Ratio data (level of measurement)

Answer 12

Strongest level of measurement. Has qualities of all other levels PLUS a “meaningful zero” that represents the absence of the quantity measured. Ex. Quarterly sales. Having $0 in sales is meaningful. Ratio data can have negative values too.

Question 13

Population

Answer 13

All of the items we are interested in observing. Ex. All of the passengers on a plane, all of the students attending CU

Question 14

Sample

Answer 14

The subset of the population that we will actually analyze. Ex. First class in the airplane, 1000 students chosen at random.

Question 15

Parameter

Answer 15

A measurement of characteristic of the population. Usually unknown since we can rarely observe the entire pop.

Question 16

Statistic

Answer 16

A NUMERICAL value calculated from a sample. Ex. Mean of ages at CU.

Question 17

Target population

Answer 17

Contains all the individuals in which we are interested.