1. A computer-readable recording medium storing instructions for predicting a result of assessment target data including a new combination of the attribute values, which when executed by a computer having at least one processor and at least one storage device, causes the computer to perform: structuring by the processor by generating a combination pattern of the attribute values by combining an attribute value of the assessment target data with an attribute value indicating an unspecified value; reconstructing by the processor by searching for data matching the combination pattern from accumulation data in the storage device in which a correlation between a combination of attribute values and a result of the combination is accumulated, and generating a plurality of subset data; setting by the processor a risk assessment index for each of the plurality of subset data generated in the reconstructing, the risk assessment index indicating a significance of a relationship between each of the plurality of subset data and the assessment target data, in such manner that, when first subset data and second subset data are included in subset data in which a combination of attribute values is statistically valid, and when the first subset data is included in the second subset data, a value indicating that the first subset data has precedence over the second subset data is set as the risk assessment index; predicting by the processor the result of assessment target data based on the accumulation data; and assessing including selecting subset data that becomes a basis of assessment, based on the risk assessment index set by the processor, and performing by the processor, an assessment on a prediction result based on the selected subset data.