#NEWLINE# def _fit_old( self ) : #NEWLINE# #INDENT# res_pooled = self . _fit_ols ( ) #NEWLINE# sigma_i = self . get_within_cov ( sigma_i . resid ) #NEWLINE# self . cholsigmainv_i = np . linalg . cholesky ( np . linalg . pinv ( sigma_i ) ) . T #NEWLINE# wendog = self . whiten_groups ( self . endog , self . cholsigmainv_i ) #NEWLINE# wexog = self . whiten_groups ( self . exog , self . cholsigmainv_i ) #NEWLINE# self . res1 = OLS ( wendog , wexog ) . fit ( ) #NEWLINE# return self . res1