Intervals design for economic variable's range and its application in the survey of household finance

In the sample survey about household finance, the respondent usually unwanted to report the true value of their key economic variables (asset and income, etc) for the reason of keeping ones privacy. One method overcoming this problem is to provide a series successive interval and let the respondent choose the right interval his economic variable satisfied. This method can mitigate the respondent double. However, the intervals design is usually based on the designer's experience and unscientific. In this paper we built a model of optimizing the analysis error of variable when we adopt this way designing the questionnaire. By using Genetic Algorithm (GA) method we give the solution of the model. In an example of investigating household's annual income, the relationship between the intervals number and the analysis error is discussed. The method proposed in this paper can help us improve the quality of survey data.