Chapter 3

Question 1

Boxplot

Answer 1

A graphical summary of data based on a five-number summary.

Question 2

Chebyshev’s theorem

Answer 2

A theorem that can be used to make statements about the proportion of data values that must be within a specified number of standard deviations of the mean.

Question 3

Coefficient of Variation

Answer 3

A measure of relative variability computed by dividing the standard deviation by the mean and multiplying by 100.

Question 4

Correlation Coefficient

Answer 4

A measure of linear association between two variables that takes on values between −1 and +1. Values near +1 indicate a strong positive linear relationship; values near −1 indicate a strong negative linear relationship; and values near zero indicate the lack of a linear relationship.

Question 5

Covariance

Answer 5

A measure of linear association between two variables. Positive values indicate a positive relationship; negative values indicate a negative relationship.

Question 6

Empirical Rule

Answer 6

A rule that can be used to compute the percentage of data values that must be within one, two, and three standard deviations of the mean for data that exhibit a bell-shaped distribution.

Question 7

Five Number Summary

Answer 7

A technique that uses five numbers to summarize the data: smallest value, first quartile, median, third quartile, and largest value.

Question 8

Geometric Mean

Answer 8

A measure of location that is calculated by finding the nth root of the product of n values.

Question 9

Interquartile Range (IQR)

Answer 9

A measure of variability, defined as the difference between the third and first quartiles.

Question 10

Mean

Answer 10

A measure of central location computed by summing the data values and dividing by the number of observations.

Question 11

Median

Answer 11

A measure of central location provided by the value in the middle when the data are arranged in ascending order.

Question 12

Mode

Answer 12

A measure of location, defined as the value that occurs with greatest frequency.

Question 13

Outlier

Answer 13

An unusually small or unusually large data value.

Question 14

Pearson product moment correlation coefficient

Answer 14

A measure of the linear relationship between two variables.

Question 15

Percentile

Answer 15

A value that provides information about how the data are spread over the interval from the smallest to the largest value.

Question 16

Point Estimator

Answer 16

A sample statistic, such as x bar, s squared, and s, used to estimate the corresponding population parameter.

Question 17

Population Parameter

Answer 17

A numerical value used as a summary measure for a population (e.g., the population mean, μ, the population variance, σ^2
, and the population standard deviation, ).

Question 18

Quartiles

Answer 18

The 25th, 50th, and 75th percentiles, referred to as the first quartile, the second quartile (median), and third quartile, respectively. The quartiles can be used to divide a data set into four parts, with each part containing approximately 25% of the data.

Question 19

Range

Answer 19

A measure of variability, defined to be the largest value minus the smallest value.

Question 20

Sample Statistic

Answer 20

A numerical value used as a summary measure for a sample (e.g., the sample mean, x̄, the sample variance, s^2, and the sample standard deviation, s).

Question 21

Skewness

Answer 21

A measure of the shape of a data distribution. Data skewed to the left result in negative skewness; a symmetric data distribution results in zero skewness; and data skewed to the right result in positive skewness.

Question 22

Standard Deviation

Answer 22

A measure of variability computed by taking the positive square root of the variance.

Question 23

Variance

Answer 23

A measure of variability based on the squared deviations of the data values about the mean.

Question 24

Weighted Mean

Answer 24

The mean obtained by assigning each observation a weight that reflects its importance.

Question 25

Z-Score

Answer 25

A value computed by dividing the deviation about the mean by the standard deviation s. A z-score is referred to as a standardized value and denotes the number of standard deviations is from the mean.