Teaching:TUW - UE InfoVis WS 2007/08 - Gruppe 07 - Aufgabe 1 - Histogram
Definitions
In statistics, a histogram is a graphical display of tabulated frequencies. A histogram is the graphical version of a table that shows what proportion of cases fall into each of several or many specified categories. The histogram differs from a bar chart in that it is the area of the bar that denotes the value, not the height, a crucial distinction when the categories are not of uniform width (Lancaster, 1974). The categories are usually specified as non-overlapping intervals of some variable. The categories (bars) must be adjacent.
[Wikipedia, 2007]
Example
Frequency Table (Salary of Employees):
| class j | Salary x i | absolute frequency n j | relative frequency | class width d j |
|---|---|---|---|---|
| 1 | 800 ≤ x < 1000 | 150 | 0,25 | 200 |
| 2 | 1000 < x < 2000 | 150 | 0,25 | 1000 |
| 3 | 2000 ≤ x ≤ 3500 | 300 | 0,50 | 1500 |
| Σ 600 | Σ 1,00 |
The height of a column is calculated as:
hj= <math>\frac {n_j}{d_j}</math>
dj is the column width.
Related Links
References
- [Wikipedia, 2007] Wikipedia, Histogram. Retrieved at: November 01, 2007. http://en.wikipedia.org/wiki/Histogram