ON THE VARIATIONS IN PERSONAL EQUATION AND 
THE CORRELATION OF SUCCESSIVE JUDGMENTS. 
By EGON S. PEARSON, Trinity dllege, Cambridge. 
CONTENTS. 
PAGE 
I. Introduction ........... 24 
II. Generalized Theory of Personal Equation ..... 25 
III. Description of the Experiments 
(a) Experiments A and B 28 
(6) Experiments C and I) 29 
(c) Experiment £ 31 
IV. Terminology and Table defining Constants 32 
V. On Methods of Reduction 
(a) Variate Difference Correlation ...... 37 
(b) Application of the Results of V. (a) 40 
VI. Experiment A. Reduction 
(a) The individual Series ....... 45 
(6) The Combination of Series ....... 59 
(c) On the possible Result of shifting the Head during the 
course of a Series . . . . . . . . 61 
(d) Summary of Results ........ 61 
VII. Experiment B. Reduction 
(«) The individual Series ........ 65 
(b) The Combination of Series . ...... 71 
(e) Comparison with Experiment A . . . . . . 73 
VIII. Experiment C. Reduction 
(«) The individual Series ........ 74 
{b) The Combination of Series 79 • 
IX. Experiment D. Reduction 
(cf) The individuiil Series 82 
(b) The Combination of Series 84 
(c) Comparison with Experiment (' . . . . . . 86 
X. Experiment E. Reduction ........ 87 
XI. Analysis of the Correlation between successive Judgments 
(a) The Theory of correlated Estimates and accidental Errors 88 
(b) Application of Theory to the Results of the Experiments . 91 
XII. Prediction 98 
XIII. Summary and Conclusions 99 
