Essential Statistics

Chapter 1: Introduction and Graphical Displays

Observe that in

Figure 1-20

the shapes are the same for the histograms and

the frequency and relative frequency polygons. The frequency and relative

frequency polygons, as well as the histograms, reflect the shape of the

distribution from which the sample was taken,

Section Review

1-7 Ogives

Ogives are graphical displays of cumulative frequency or cumulative relative

frequency distributions. They are useful when one wants to determine how

many or what proportion of values are smaller than or equal to a specified

value in the data set. If the ogive is displayed for grouped data, then the

ogive can be used to determine how many or what proportion of values are

smaller than the upper class limit or the class mark for a specified class.

Definition: Ogive

An ogive is a line graph of a cumulative frequency or cumulative relative

frequency distribution.

Example 1-9:

Use the information from

Table 1-4

to construct a frequency

ogive and a relative frequency ogive.

Table 1-4

is repeated below for

reference.