bivariate density function

例句：

1. 1.The researchers used a bivariate analysis to study the relationship between income and education.
   研究人员使用双变量分析来研究收入和教育之间的关系。
2. 2.In this study, we used a bivariate regression model to predict the future performance of the company.
   在这个研究中，我们使用了一个双变量回归模型来预测公司的未来表现。
3. 3. The bivariate correlation coefficient measures the strength and direction of the relationship between two variables.
   双变量相关系数衡量两个变量之间强度和方向的关系。