In general, traditionalregression analysisstudies the relationship between the independent variable and the conditional expectation of the dependent variable,and the corresponding regression model obtained can estimate the conditional expectation of the dependent variable from that of the independent variable；Quantile regression studies the relationship between the independent variable and the conditional quantile of the dependent variable,,and the corresponding regression model obtained can estimate the conditional quantile of the dependent variable from the independent variable.Compared with traditional regression analysis that only yields the central trend of the dependent variable, quantile regression can further infer the conditional probability distribution of the dependent variable. Quantile regression belongs toone ofthe nonparametric statistical methods.