Activity: Graphical Displays – Comparative Bar Charts and Pie Charts (AP Statistics)
Night Herons and cattle egrets are species of birds that feed on aquatic prey in shallow water. These
birds wade through shallow water, stalking submerged prey and then striking rapidly and downward
through the water in an attempt to catch the prey. The article “Cattle Egrets Are Less Able to Cope with
Light Refraction Than Are Other Herons” (Animal Behavior [1999]: 687 – 694) gave data on outcome
when 240 cattle egrets attempted to capture submerged prey. Suppose that the scientists also observed
240 Night Herons.
Complete the table for the following data
Category Cattle Egret Data Night Heron Data
Frequency Relative Frequency Frequency Relative Frequency
First Attempt 103 82.0%
Second Attempt 41 15.0%
Third Attempt 2 3.0%
Not Caught 94 0.0%
Create a comparative bar chart with the attempts on the horizontal axis, two bars per attempt (one for
cattle egret and one for night heron), and frequency on the vertical axis.
Create two pie charts. Each pie chart should have the different categories represent the different slices
and the size of the slice should represent the relative frequency. Each bird should have one pie chart.
Discuss the relevance of the question ‘which bird is the better hunter?’
What might be some reasons for the differences in the two birds data?
What are the advantages of each type of chart for this data?
Which type of chart highlights the important patterns most clearly?
Category Cattle Egret Data Night Heron Data
Relative
Frequency Frequency Relative Frequency
Frequency
First Attempt 103 0.429166667 196.8 82.00%
Second Attempt 41 0.170833333 36 15.00%
Third Attempt 2 0.008333333 7.2 3.00%
Not Caught 94 0.391666667 0 0.00%
250
200
150
Cattle Egret Data
100
Night Heron Data
50
0
First Attempt Second Third Not Caught
Attempt Attempt
Cattle Egret Data
First Attempt Second Attempt Third Attempt Not Caught
39% 43%
17%
1%
Not Caught
Third Attempt
3%
Night Heron Data 0%
Second Attempt
15%
First Attempt
82%