[其他] [求助]demeaned是一种怎么样的数据处理方法？ [推广有奖]

我看到一篇文章，里面说将变量对其平均值demeaned，这样就能起到控制固定效应的作用。请问，demeaned是一种怎么样的数据处理方法？

原文如下：

The first model in Holmes (1999) is specified as:
 PII*=aEMP*+u*
where the asterisk means that the variable is demeaned by its industry average. By demeaning the variables, this specification controls for industry fixed effects.