A set of data introduced by Bortkiewicz. It illustrates the fact that the frequencies of occurrence of unlikely events (see sample space) follow a Poisson distribution even when there may be variations in the probabilities of the events. Bortkiewicz's data refer to the numbers of deaths in each corps of the Prussian Army during the period 1875–94. The data, given in the table, show significant variations from year to year and from corps to corps, but have mean (0.70) and variance (0.76) approximately equal.
CORPS | 1875 | 1876 | 1877 | 1878 | 1879 | 1880 | 1881 | 1882 | 1883 | 1884 | 1885 | 1886 | 1887 | 1888 | 1889 | 1890 | 1891 | 1892 | 1893 | 1894 |
|---|
G | 0 | 2 | 2 | 1 | 0 | 0 | 1 | 1 | 0 | 3 | 0 | 2 | 1 | 0 | 0 | 1 | 0 | 1 | 0 | 1 |
I | 0 | 0 | 0 | 2 | 0 | 3 | 0 | 2 | 0 | 0 | 0 | 1 | 1 | 1 | 0 | 2 | 0 | 3 | 1 | 0 |
II | 0 | 0 | 0 | 2 | 0 | 2 | 0 | 0 | 1 | 1 | 0 | 0 | 2 | 1 | 1 | 0 | 0 | 2 | 0 | 0 |
III | 0 | 0 | 0 | 1 | 1 | 1 | 2 | 0 | 2 | 0 | 0 | 0 | 1 | 0 | 1 | 2 | 1 | 0 | 0 | 0 |
IV | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 0 |
V | 0 | 0 | 0 | 0 | 2 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 0 |
VI | 0 | 0 | 1 | 0 | 2 | 0 | 0 | 1 | 2 | 0 | 1 | 1 | 3 | 1 | 1 | 1 | 0 | 3 | 0 | 0 |
VII | 1 | 0 | 1 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 0 | 0 | 2 | 0 | 0 | 2 | 1 | 0 | 2 | 0 |
VIII | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 1 | 0 | 1 |
IX | 0 | 0 | 0 | 0 | 0 | 2 | 1 | 1 | 1 | 0 | 2 | 1 | 1 | 0 | 1 | 2 | 0 | 1 | 0 | 0 |
X | 0 | 0 | 1 | 1 | 0 | 1 | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 0 | 2 | 1 | 3 | 0 | 1 | 1 |
XI | 0 | 0 | 0 | 0 | 2 | 4 | 0 | 1 | 3 | 0 | 1 | 1 | 1 | 1 | 2 | 1 | 3 | 1 | 3 | 1 |
XIV | 1 | 1 | 2 | 1 | 1 | 3 | 0 | 4 | 0 | 1 | 0 | 3 | 2 | 1 | 0 | 2 | 1 | 1 | 0 | 0 |
XV | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 0 | 0 | 0 | 2 | 2 | 0 | 0 | 0 | 0 |
Prussian horse-kicks. Numbers of deaths due to horse-kicks in each corps of the Prussian Army during the period 1875–94.