140

G76

suitable method will exclude that instance from the sample. Moreover, if there be any reason to suspect that an instance has in any important degree been brought to our attentive experience by causes connected with its being or not being P, our suitable method will exclude it. Furthermore, supposing that we intend to reach such a degree of approximation that all the figures in the first 2 places of decimals shall exactly be correct, if that a 5 in a certain place of decimals, say the 2nd after the decimal-point, be the largest that will be a matter of no concern in the expression of the probability-limit of the ratio of future Ss that are P to all the Ss, then the suitable rule will provide for the collection of a number of instances equal to 0.45434 x 100P. If, however, we are sure that one tenth