Volume I 
APRIL, 1902 
No. 3 
ON THE SYSTEMATIC FITTING OF CURVES TO 
OBSERVATIONS AND MEASUREMENTS. 
By KARL PEARSON, F.R.S., University College, London. 
CONTENTS. 
Page 
Introductory Note. .............. 266 
(1) General Theorem. If the values of the constants of a curve be found by the 
method of moments, the fit will be good. ........ 267 
(2) On the discovery of the area and moments of a curve given by a series of isolated 
observations. .............. 272 
(3) Comparison in a special case of method of least squares and method of moments 279 
(4) On the discovery of the area and moments vi'heii tlie data consist of the 
frequencies falling within certain elementary ranges. ..... 282 
(5) Illustration I. To fit a curve of type 
Calculation of moments and constants for tlie fecundity distribution of brood- 
mares. ............... 289 
(6) Illustration II. To fit a curve of type 
Observations of Thiele 292 
(7) Illustration III. To fit a curve of type 
y = a sin {nx + a), 
or a sine-curve, when a part only of the range has been observed. 
Observations of Chree. ............ 295 
(8) Illustration IV. To fit Makeham's curve to mortality statistics 298 
Biometrika i 26 
I 
