Set of sample identification information and representative-point designating data is generated in accordance with performance data or the like, and sample data is obtained by referring to a database in accordance with the generated sample identification information. If necessary, the thus-obtained sample data is adjusted or modified on the basis of the representative-point designating data. Characteristic of the sample data can be controlled appropriately and efficiently by the representative-point designating data specifying representative sample points for which sample data adjustment is to be performed. For example, particular sample data that is located at a given representative sample point designated by the representative-point designating data is adjusted in accordance with adjustment information, and other sample data that is located at another sample point is adjusted simultaneously with such adjustment at the representative sample point.