But parameters of age, period and cohort are not uniquely estimable because of the exact linear dependency among the three variables, so many approaches have been proposed.

然而模型的三因素间存在着完全线性依赖性，使参数不能得出唯一的估计值，许多学者提出了各种方法加以解决。

youdao

But parameters of age, period and cohort are not uniquely estimable because of the exact linear dependency among the three variables, so many approaches have been proposed.

然而模型的三因素间存在着完全线性依赖性，使参数不能得出唯一的估计值，许多学者提出了各种方法加以解决。

youdao