<p>xtreg urb pcg tin tie,fe</p><p>xttest2</p><p>出现了这样的一行字Correlation matrix of residuals is singular.not possible with test,为什么会出现这种情况呢,该怎么办才能检验出结果呢</p><p>谢谢<br/></p>
请问,我是长面板数据,也更新了xttest2命令,但是仍然报错,Correlation matrix of residuals is singular. not variables. test tests only linear hypotheses. 错误代码的提示信息是,You requested a test of a hypothesis that is nonlinear in the variables. test tests only linear hypotheses. Use testnl.