Histograms

Definition of a Histogram A Histogram displays a range of values of a variable that have been broken into groups or intervals. Histograms are useful if you are trying to graph a large set of quantitative data To make a Histogram, you divide the range of data into intervals of equal length, count the number of observations in each interval, and represent each interval with a bar indicating the number of observations.

Disenfranchisement Rates for all 50 States 8.1 24.9 6.6 9.2 1.5 17.1 3.9 14 11.3 2.8 1.2 4.6 16.1 3.1 3 10.3 5 17.4 7.2 4 2.4 7.9 24.7 14.2 8.3 14.3 16 18.9 5.7 0.8 0.7 3.5 12.9 6.2 4.2 2.6 3.7 8.4

Step 1: Sort the Data from Lowest to Highest 2.6 4 7.9 14 2.8 8.1 14.2 0.7 4.2 8.3 14.3 0.8 16 1.2 4.6 8.4 16.1 1.5 3 5 9.2 17.1 3.1 5.7 17.4 3.5 6.2 10.3 18.9 2.4 3.7 6.6 11.3 24.7 3.9 7.2 12.9 24.9

Step 2: Determine how many groups of data you want to have. For example, we’ll use 5 groups Step 3: Determine the approximate range of the set of data 0% through 24.9% (approximately 25%) Step 4: From Steps 2 and 3, determine the range of each individual group I decided to have 5 groups. The range is from 0% - 25%. 25% divided by 5 is 5%. So each group should have a range of 5%.

Step 5: Make a list of the groups you will be using. Step 6: Using your data, count how many numbers fall into each group Group 1: 0% - 4.99% Group 2: 5% - 9.99% Group 3: 10% - 14.99% Group 4: 15% - 19.99% Group 5: 20% - 25% 25 12 6 5 2

Step 7: graph each group 25 12 6 5 2