Diagram IV. Comparison of the theoretical frequency curve y = 1500 π ( 1 + x 2 s 2 ) − 2 {\displaystyle y={\frac {1500}{\pi }}\left(1+{\frac {x^{2}}{s^{2}}}\right)^{-2}} , with an actual sample of 750 cases.
Scale of Standard Deviation of the sample