64 
Oil the Variations in Personal Equation 
It will be shown in a later section that the values of R^', k = l ... 13, can be fitted 
very closely by a curve of the type 2/ = P + vvhere p, q, and r are constants. 
Finally it was shown that the correlation of successive judgments could not be 
due to a shifting of the head during the course of observation, although this 
might perhaps be one of many contributory causes. 
Experiment A. TRISECTION. correlation -Interval Diagram. 
4 5 6 7 8 9 10 
Interval between successive judgments 
Fig. 8. 
In Figure 8 the values of R^, R/, and R/' (for linear sessional change) are 
plotted to k; the theoretical curves of the Equations (xlix) and (Ivi) shown in the 
Figure will be discussed in Section XI, and also the points referred to as Rk". 
