PARAMETER CONTROLLING APPARATUS AND MULTISTAGE COLLATION APPARATUS

A parameter controlling apparatus calculates similarity variation distribution of different data and that of identical data. The parameter controlling apparatus creates a collation break-off rate function and an error probability function based on the similarity variation distribution of the different data and that of the identical data, respectively, and creates a total collation time function and a total error probability function based on the collation break-off rate function and the error probability function. The parameter controlling apparatus creates a constraint equation based on the total collation time function, the total error probability function, total collation time constraint parameters, and total error probability constraint parameters. The parameter controlling apparatus calculates a parameter group that optimizes an objective function constituted by the collation break-off rate function, the error probability function, the total collation time function, and the total error probability function among combinations of parameters that satisfy the constraint equation.