Godfrey H. Thomson . 305 
Now clearly, with a distribution of this sort, it is very important that the 
boundary between the values that are to be rejected and those that are to be 
accepted should l)e chosen with the greatest care, and not arbiti-arily but scientific- 
ally. Either sound theoretical reasons should be given for the choice of the 
correctional standard, or the choice should be based empirically on expei-iments in 
zero 
Descending the hierarchy — ► 
Fig. 2. 
material where the truth is known a priori, as in the above dice experiments. For 
obviously, by moving this boundary, we can make the final average take on almost 
any value. Another point is that the criterion rushes to infinity at such speed 
that its probable error must be enormous. Dr Hart and Professor Spearman, 
