Graphic Methods for Presenting Facts
^/ ,. ' ^ ^ , Fig. i6i. Curves to Show the Percentages of the Total
Population of Prussia in 1892 and in 190 1 that Received Various Percentages of the Total Income as Considered on the Horizontal Scale
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30 40 50 60 70
Percents of Total I ncome
80 90 100
EQUALITY PRUSSIA 1892. PRUSSIA 1901
M. O. Lorenz, in the Publications, the American Statistical Assn.
If incomes were all equal the relation of population and income would be expressed by the straight diagonal line. The amount of inequality between various incomes is shown by the amount the curve diverges from the straight line. There was greater inequality of incomes in Prussia in 1901 than in 1892
a long line and ranked according to income. The people in this line could be counted off into several equal groups so that each group would contain say 10 per cent of the total number. It would then be simple to compute the income of each group as a percentage of the combined income for all groups. The resulting group percentages would be plotted cumulatively as the dependent variable on a chart for which percentages of population would be the independent variable. Fig. 161 unfortunately shows the independent variable used for the vertical scale. A better arrangement may be seen by observing the illustration through the back of the paper with the two zeros appearing at the lower left-hand corner.