II. — On the Validity of the Ergograph as a Measurer of 

 Work Capacity 



A Contribution to Practice and Learning 



BY THADDEUS L. BOLTON AND ELEONORA T. MILLER 

 INTRODUCTION 



The purpose of the experiment discussed in the following 

 pages was to test the validity of the ergograph as a measurer of 

 the capacity of an individual for muscular work ; that is, to deter- 

 mine in how far the ergograph records might be relied upon as 

 giving a fair estimate of work capacity. The chief consideration 

 in this, as in any psychological problem where it is a question of 

 measuring processes accurately, is to determine the probable 

 value of a single observation or small number of observations 

 made within a few days, as furnishing sufficient data upon which 

 to generalize. The treatment of this question in connection with 

 the present problem involves a consideration of the character 

 and direction of influences which are most likely to affect a single 

 record or group of records, and thus render this record or group 

 of records unreliable as an indication of work capacity. 



Thus stated, the problem becomes a study of the variations 

 that take place in a series of records taken under reasonably 

 uniform conditions. Investigators have used the ergograph upon 

 children and adults upon the assumption that a single record or 

 a small number of records taken within a period of a few days 

 is a fair measure of the amount of work they can do, and in the 

 long run can be relied upon in a comparative estimate of the 

 individuals studied. Are there not influences operative in a single 

 test or a small number which do not affect a long series, and 

 likewise, influences operative in a long series which do not enter 

 into a single test? Do records change relatively in the course 

 of a long series so as to invalidate those at the beginning of the 



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