Fisher’s ideas were developed jointly by the émigré Polish mathematician Jerzy Neyman (1894-1981) and Egon Pearson (1895-1980). ey added two additional elements. First, if the null hypothesis is rejected, then the alternative hypothesis should be accepted and one treatment should be regarded as superior to the other. Second, they introduced the notion of errors of the first kind involving rejection of the null hypothesis when it is true (known as a type I error); and errors of the second kind where the null hypothesis is accepted when it is false (known as a type II error). ese are, respectively, false negative and false positive results, but the terminology of type I and type II errors is entrenched in the statistical literature.