Chapter 2: Graphical Descriptions of Data

Question 1

distribution

Answer 1

a way to describe the structure of a particular data set or population

Question 2

frequency distribution

Answer 2

a display of the values that occur in a data set and how often each value, or range of values, occurs

Question 3

frequencies (f)

Answer 3

the numbers of data values in the categories of a frequency distribution

Question 4

class

Answer 4

a category of data in a frequency distribution

Question 5

class width

Answer 5

the difference between the lower limits or upper limits of two consecutive classes of a frequency distribution

class width = (highest value - lowest value) ÷ number of classes

Question 6

lower class limit

Answer 6

• the smallest number that can belong to a particular class
• same number of decimal places as the largest number of decimal places in the data

Question 7

upper class limit

Answer 7

• the largest number that can belong to a particular class
• same number of decimal places as the largest number of decimal places in the data

Question 8

class boundary

Answer 8

• the value halfway between the upper limit of one class and the lower limit of the next class

class boundary = (Class 1 upper limit + Class 2 lower limit) ÷ 2

• After finding one class boundary, add or subtract the class width to find the next class boundary. The boundaries of a class are typically given in interval form: lower boundary–upper boundary

Question 9

midpoint (class mark)

Answer 9

(lower limit + upper limit) ÷ 2

Question 10

relative frequency

Answer 10

relative frequency = f ÷ n

Question 11

sample size

Answer 11

n = Σf_i

Question 12

cumulative frequency

Answer 12

• the sum of the frequencies of a given class and all previous classes
• the cumulative frequency of the last class equals the sample size (Σf_i)

Question 13

pie chart

Answer 13

• shows how large each category is in relation to the whole
• round each angle measure to the nearest whole degree
• qualitative data

Question 14

bar graph

Answer 14

• bars represent the amount of data in each category
• one axis displays categories, and the other displays frequencies
• qualitative data

Question 15

Pareto chart

Answer 15

• bar graph in descending order
• typically used with nominal data
• qualitative data

Question 16

side-by-side bar graph

Answer 16

• a bar graph that compares the same categories for different groups
• qualitative data

Question 17

stacked bar graph

Answer 17

• bar graph that compares the same categories for different groups and shows category totals
• qualitative data

Question 18

histogram

Answer 18

• a bar graph of a frequency distribution of quantitative data
• horizontal axis is a number line
• quantitative data

Question 19

relative frequency histogram

Answer 19

• a histogram in which the heights of the bars represent the relative frequencies of each class rather than simply the frequencies
• quantitative data

Question 20

frequency polygon

Answer 20

• visual display of the frequency of each class of quantitative data that uses straight lines to connect points plotted above the class midpoints
• quantitative data

Question 21

ogive

Answer 21

• shows the cumulative frequency of each class, created by adding a 0 for the first data point and joining the points together with line segments
• quantitative data

Question 22

stem-and-leaf plot

Answer 22

• retains the original data
• the leaves are the last significant digit in each data value and the stems are the remaining digits
• requires a key
• quantitative data

Question 23

dot plot

Answer 23

• displays the data without grouping; only data that are exactly the same appear together
• retains the original data by plotting a dot above each data value on a number line
• quantitative data

Question 24

line graph

Answer 24

uses straight lines to connect points plotted at the value of each measurement above the time it was taken

Question 25

required labels on a graph

Answer 25

* title: what it's about * axes: categories and data boundaries/classes * source: where the data came from

Question 26

time-series graph

Answer 26

used to display a variable whose values change over time

Question 27

cross-sectional graph

Answer 27

graph that displays information gathered at a single point in time

Question 28

pictograph

Answer 28

bar graph that uses pictures of objects instead of bars

Question 29

important aspects of graphs

Answer 29

* appropriateness (type of graph) * scaling * shape * uniform * symmetric * skewed to the right * skewed to the left *

Question 30

uniform graph

Answer 30

the frequency of each class is relatively the same

Question 31

symmetric

Answer 31

the data lie evenly on both sides of the distribution

Question 32

skewed to the right

Answer 32

when the majority of the data fall on the left side of the distribution; the "tail" of the distribution is on the right

Question 33

skewed to the left

Answer 33

when the majority of the data fall on the right side of the distribution; the "tail" is on the left

Question 34

outlier

Answer 34

a data value that falls outside the shape of the distribution