chapter 1

Question 1

What are individuals?

Answer 1

the objects described by a set of data. Individuals may be people, but they may also be animals or things.

Question 2

What is a variable?

Answer 2

any characteristic of an individual. A variable can take different values for different individuals.

Question 3

What is a categorical variable?

Answer 3

A categorical variable places an individual into one of several groups or categories.

Question 4

What is a quantitative variable?

Answer 4

takes numerical values for which arithmetic operations such as adding and averaging make sense. The values of a quantitative variable are usually recorded with a unit of measurement such as seconds or kilograms.

Question 5

What is the distribution of a variable?

Answer 5

tells us what values it takes and how often it takes these values.

Question 6

What is a histogram?

Answer 6

A graph of the distribution of one quantitative variable. The horizontal axis is marked in the units of measurement for the variable. The range of the data is divided into classes of equal width. Bars on the graph each represent a class, with the base of each bar covering the class on the horizontal axis. The vertical axis displays the scale of counts, and each bar’s height is the class count.

Question 7

What does it mean when a distribution is skewed to the right?

Answer 7

extends longer to the right or the tail is on the right

Question 8

What does it mean when a distribution is skewed to the left?

Answer 8

extends longer to the left or the tail is on the left

Question 9

What is a stemplot?

Answer 9

A graph of the distribution of a quantitative variable. Each observation is shown as a stem, consisting of all but the final (rightmost) digit, and a leaf, the final digit. The unique stems are stacked in a vertical column with the smallest at the top, and a vertical line appears to the right of the column. Each leaf for a stem appears in a row to the right of the stem.

Question 10

What range of data sets are not suitable for stemplots?
-small
- large

Answer 10

stemplots do not work well for large data sets, where each stem must hold a large number of leaves.

Question 11

Answer 11

A

Question 12

Answer 12

B

Question 13

Answer 13

B

Question 14

Answer 14

Individuals are students who have finished medical school.

Five, in addition to “Name,” “Age” (in years), and “USMLE” (score points) are quantitative. The others are categorical.

Question 15

Make a stemplot of the following data, 58.5, 57.7, 58.4, 59.1, 58.7, 57.5, 59.5, 58.1

Answer 15

Question 16

Is this histogram skewed right, left, or symmetric

Answer 16

skewed right

Question 17

Answer 17