There is provided a method including inputting a plurality of symbol strings and attribute information desired to be extracted from each symbol string; selecting a plurality of functions from a predetermined function group including a function for converting a symbol string into a numerical value, and generating a plurality of feature quantity functions for outputting a feature quantity from the symbol string by combining the plurality of functions; inputting each symbol string to each feature quantity function, and calculating a feature quantity corresponding to each symbol string; executing machine learning using the attribute information corresponding to each symbol string and the feature quantity corresponding to each symbol string, and generating an estimation function for estimating the attribute information from the feature quantity; and outputting the feature quantity functions and the estimation function.