In the statsmodels time series analysis AR and ARMA models, the freq
argument can be "a Pandas offset or ‘B’, ‘D’, ‘W’, ‘M’, ‘A’, or ‘Q’."
What do ‘B’, ‘D’, ‘W’, ‘M’, ‘A’, and ‘Q’ mean? I'm guessing that D is 'daily', W is 'weekly', M is 'monthly', A is 'annually', and that Q is 'quarterly', but I can't figure out what B is, and I can't find any documentation that confirms (or disconfirms) my guesses.