In order to increase a response rate, a data mining server selects an advertisement mail among a plurality of advertisement mails to be sent in a test transmission to personal computers selected at random among those owned by registered customers. The data mining server then computes learning parameters for each of sent advertisement mails from learning data created from response results of the test transmissions. Then, the data mining server applies learning parameters of each advertisement mail to original assessment data of other personal computers each serving as an object of an actual transmission to find predicted values. Subsequently, the data mining server extracts assessment data with largest advertisement-mail predicted values from the original assessment data. The data mining server then synthesizes the extracted pieces of assessment data. Finally, the data mining server sorts the synthesized pieces of assessment data in an order of decreasing customer predicted values to create an assessment chart.