Displaying small counts
When the range of values in a discrete data set is small, a histogram can be drawn with class width 1 without appearing too jagged. These classes are centred on the possible values in the data set (i.e. 1, 2, 3, etc).
Such a histogram can be improved by narrowing the rectangles so that they do not touch, since this emphasises the discrete nature of the data. The resulting display is called a bar chart of the data.
For discrete data, bar charts are preferable to histograms, provided this does not result in too many classes.
Hurricanes in the North Atlantic
The table below shows the numbers of hurricanes in the North Atlantic each year between 1910 and 2009.
Decade | Year | |||||||||
---|---|---|---|---|---|---|---|---|---|---|
Beginning | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 |
3 4 2 4 11 4 5 9 8 8 |
3 4 2 4 8 8 6 7 4 9 |
4 2 6 4 6 3 3 2 4 4 |
3 3 9 5 6 7 4 3 4 7 |
0 5 6 7 6 6 4 5 3 9 |
4 1 5 5 9 4 6 7 11 15 |
11 8 7 3 4 7 6 4 9 5 |
2 4 3 5 3 6 5 3 3 5 |
3 4 3 6 7 5 5 5 10 8 |
1 3 3 7 7 12 5 7 8 3 |
The diagram below shows a histogram of the data.
Use the slider to change the histogram into a bar chart — the best display of the data.