1. A computer-readable, non-transitory storage medium storing a program for causing a computer to execute a process, the process comprising: first generating, from data of a plurality of model expressions, each including a residual term and representing a relationship between input parameters and output evaluation indicators, and data of a range of the residual term for each of the plurality of model expressions, a first problem to calculate a first region that is capable of being feasible with the plurality of model expressions, value ranges of the input parameters and the range of the residual term for each of the plurality of model expressions and a second problem to calculate a second region that is always feasible with the plurality of model expressions, the value ranges of the input parameters and influence of the range of the residual term for each of the plurality of model expressions, wherein the range of the residual term is a range of residuals for values of the output evaluation indicators, which are calculated by a model expression including the residual term; first causing a processing unit configured to calculate a feasible region by a quantifier elimination method to calculate a first feasible region for the first problem and a second feasible region for the second problem to obtain first data of the first feasible region and second data of the second feasible region; superimposing the first feasible region and the second feasible region based on the first data and the second data; and displaying, on a display device, the first feasible region and the second feasible region which have been superimposed.