6. newey(integer): newey specifies the number of lags for estimation of Newey-West consistent standard errors. asreg allows option newey to be used in both the rolling regressions
and Fama-McBeth regressions. In the rolling regressions, newey will work only when option se is used. Also, please note that without using option newey, option se estimates normal
standard errors of OLS. This option accepts only integers, for example newey(1) or newey(4) are acceptable, but newey(1.5) or newey(2.3) are not.