Notes on the Constant Term in the Fixed Effect Model

In stata, the fixed effect model(xtreg y x1 x2 x3, fe) report a constant term. The underline estimate is \[y_{it} - \bar{yr} + \bar{\bar{y}} = a + (x_{it} - \bar{x_{i}} + \bar{\bar{x}})) \alpha + (\epsilon_{it} - \bar{e_i} + \bar{v})\] with the constrant \(\bar{v}\) equals to 0. Details can be found on Stata’s website.

In R, plm package does not calculate the some whate artificial¹ intercept for within models.