The numerical measure of the success of predictions.
The numerical measure of the success of predictions.
复制标题
DOI:
10.1126/science.ns-4.93.453-a
复制
发表时间:
1884-11-14
期刊:
影响因子:
--
通讯作者:
Peirce, C S
中科院分区:
文献类型:
--
作者:
Peirce, C S
Suppose we have a method by which questions of a certain kind, presenting two alternatives, can in every case be answered, though not always rightly. Suppose, further, that a large number of such answers have been tabulated in conlparison with the events, so that we have given the following four numbers:-(aa), the nurnber of questions for which the answers were the first way and the events the first way;(ab)', the number of questions for which the answers were the first way and the events the second way;(ba), the number of questions for wbich the answers were the second way and the events the first way·(bb), the~ umber of questions for which the answers were the second way and the events the second wa~.Then the problem is, frorn these data to assign a numerical measure to the success or science of the method by which the answers have been produced. Mr. GK Gilbert (A1ner. 1neteorologicaljournal, Sep-tember, 1884) has recently proposed a formula for this purpose; and I desire to offer another. I make use of two principles. The first is, that any two rnethods are to be regarded as equal approximations to complete knowledge, which, in the long-run, would give the same values for (aa),(ab),(ba), and (bb). The second principle is, that if the answers had been obtained by selecting a determinate proportion of the questions by chance, to be answered by an infallible witness, while the rest were answered hy an utterly ignorant person at random (using yes and no, vith determinate relative frequencies), then the approxinlation to kno,,'ledge in the answers so obtained would be measured by the fraction expressing the proportion of questions put to the infallible witness. The second witness may know how often he ought to answer'yes;'but I give him no credit for that, because he is ignorant when he ought to answer, yes.'