PSYCHOLOGY IN INDUSTRY 



compared with their actual success as measured by amount 

 of sales. Among the men so examined were forty salesmen 

 for a food products company. To the dismay of the investi- 

 gators, when the test scores were compared with the 

 men's sales production records, the correlation was almost 

 zero. This seemed to be a severe indictment of the test 

 as a measure of intelligence. Then came the war, and with 

 it a vast experience in personnel classification and intelli- 

 gence examining. The psychological tests proved their 

 worth as indicators of mental alertness. So, when Major 

 Yoakum, with his background of Army experience, 

 assumed direction of the Bureau of Personnel Research in 

 1919, he knew that the intelligence test methods were 

 valid, and he sought a fresh explanation of the riddle in the 

 findings of 1916. Using the same data, he computed the 

 correlation between test performance and length of experi- 

 ence with the company. The correlation was not zero. 

 It was negative: —0.40. In other words, the brighter the 

 salesman, the sooner he tended to leave the employ of that 

 concern. Yoakum repeated the experiment with seventy- 

 six salesmen of the same company, using the best available 

 adult intelligence examination. The correlation between 

 test scores and length of experience was —0.46. A job 

 analysis showed that the work required of these men was 

 largely routine order-taking. The pay was meager. Chances 

 of promotion were slight. Only plodders were content to 

 remain long enough to get necessary experience and build 

 up a creditable sales record. Examining the intelligence 

 scores again, it was apparent that there was an upper limit 

 as well as a lower limit within which the chances were 

 large that an applicant for a position with this concern 

 would make good. Below this zone he lacked the necessary 

 mental ability. Above it the probabilities were that he 

 would not be content to remain long enough to learn his 

 work thoroughly. The earlier form of psychological test 



[141] 



