If β ^ (\ displaystyle \ scriptstyle (\ hat (\ beta))) is an ordinary least squares estimator in the classical linear regression model (that is, with normally distributed and homoscedastic error terms), and if the true value of parameter β is equal to β, then the sampling distribution of the t - statistic is the Student 's t - distribution with (n − k) degrees of freedom, where n is the number of observations, and k is the number of regressors (including the intercept).
how many degrees of freedom does the​ t-statistic have
n − k) degrees of freedom, where n is the number of observations, and k is the number of regressors (including the intercept).