Incorrect T-Stats in FamaMacBeth.py

[Liam3851]

Small bug in the FamaMacBeth class at lines 105-106-- the printed form of the regression results gives the STD twice, rather than the t-stat:

std_beta = self._results['std_beta'][i]
t_stat = self._results['std_beta'][i]


Last one should be t_stat instead of std_beta the second time.

[wesm]

fixed in git HEAD