Nomograph for Computing Bi-Serial Correlations
Jack W. Dunlap · Psychometrika · 1936
The widespread use of bi-serial r in item analysis makes a quick and accurate method of evaluating the formula desirable. Such a method is provided by homographs. Dunlap and Kurtz in their Nomograph No. 47 give a method of solving the better known statement of the formula, namely (1)