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12 UNIT 1 Exploring One-Variable Data

EXAMPLE What’s on the radio? Skills 2.A, 2.B
Displaying categorical data: Bar graphs

PROBLEM: Nielsen Audio, the rating service for radio audiences, places U.S.

radio stations into categories that describe the kinds of programs they broadcast.
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The frequency table summarizes the distribution of station format in a recent
10
year. Make a frequency bar graph to display the data. Describe what you see.
Number of Number of
Format stations Format stations
Adult contemporary 1357 Religious 3837 ACORN 1/Alamy Stock Photo
All sports 669 Rock 1466
Classic hits 1140 Spanish language 1228
Country 2200 Variety 1257
News/talk/information 2002 Other formats 1769
Oldies 405 Total 17,330
SOLUTION:
4000
3500 To make the bar graph:
3000
Number of stations 2500 1. Draw and label the axes.
2000
2. “Scale” the axes. The larg-
1500
est frequency is 3837, so we
1000
500 choose a vertical scale from 0
to 4000, with tick marks 500
0 Oldies Rock Variety units apart.
Adult contemporary All sports Classic hits Country News/talk/info Religious Spanish language Other formats 3. Draw bars above the category
names.

Radio station format
On U.S. radio stations, the most common formats are Religious (3837), Country (2200), and News/Talk/
Information (2002), while the least common formats are Oldies (405) and All Sports (669). Moderately common
formats offered by a similar number of stations include Classic Hits (1140), Spanish Language (1228), Variety
(1257), Adult Contemporary (1357), and Rock (1466). There are 1769 stations with Other formats.

FoR PRAcTIce, TRY eXeRcISe 1
Adult contemporary
7.83%
All sports
Other 3.86% PIE CHARTS
Variety formats
7.25% Classic hits Here is a pie chart of the radio station format data from the
10.21% 6.58%
Spanish preceding example. Notice that this graph shows the relative
language frequency for each response category. For instance, the “Span-
ish language” slice makes up 7.09% of the graph because the
Country

Rock 12.69% relative frequency for this category is 1228/17,330 = 0.0709 =
8.46% 7.09%.
News/Talk/Info
Religious 11.55%
22.14% DEFINITION Pie chart
A pie chart shows each category as a slice of the “pie.” The
Oldies areas of the slices are proportional to the category frequencies
2.34% or relative frequencies.
Radio station format
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