1. A method for predicting whether data that is not yet known to be positive or negative with respect to a certain problem is positive or negative, comprising: a positive example accessing step of accessing a positive example data storage unit pre-storing groups of positive example data constituting correction examples for the problem; an existence determination step for determining whether or not the data exists in the positive example data groups; an appearance probability calculating step for calculating typical probability of appearance of the data when the data does not exist in the positive example data groups; and an negative example likelihood calculation step for calculating a probability of appearance of the data in the positive example data group based on the typical probability of appearance and taking the probability as a likelihood of an negative example.