1　前言协方差分析是在直线回归与方差分析结合的基础上发展起来的一种统计方法。假如我们要比较城市学生与农村学生肺活量的差异 ,即使用同年龄、同性别的学生进行比较 ,仍存在某种偏差。因为 ,通常已知肺活量与身高存在直线回归关系 ,所以 ,要考虑二者肺活量的差异是否因身高 1 Introduction Covariance analysis is a statistical method developed on the basis of linear regression and analysis of variance. If we want to compare the difference in lung capacity between city students and rural students, some differences still exist when students of the same age and same sex are compared. Because it is generally known that there is a linear regression between vital capacity and height, it is important to consider whether the difference in vital capacity between the two is due to height