EMPLOYMENT PSYCHOLOGY 
cient to which it is applied is the true correlation of the two 
variables in question. P.E., may be obtained quickly from 
tables given by Pearson (135), Toops and Miner (204), and 
Rugg (157), or by graphic methods given by Pearson (135) 
and Toops (202). 
The probable error of a correlation ratio is (233, p. 352): 
I—n? 
2 PEy=06745—— 
The probable error of biserial 7 is (86, p. 249) 
P.E.,=0.6745———— 
(30) 0.4748 % 
The formula for the probable error of the coefficient of 
mean square contingency is given by Kelley (86, p. 269). 
The formula given there applies to Pearson’s formula for the 
coefficient of mean square contingency, which is more com- 
plex than Yule’s. 
The general formula for the probable error of » obtained 
by the fourfold table method is given by Kelley (86, p. 258). 
The formula to be used when the division lines are at the 
medians (method of unlike signs) is (86, p. 257): 
Kelley gives the formulas for the probable error of # cor- 
rected for attenuation (86, pp. 209-210). We shall quote 
here only the formula for the probable error of corrected 
for attenuation by the use of formula 4. Let the corrected 
value of »,- be represented by 7. 
7 I 
(32) PE, =osrstit 
I 72x. x, I 
+ (Fo i TA ras Frits 1) 
LL Ton a Mt 
+(e 1 lope Ty, 0} 
188"