what is the formula to use for the time series regression? time series model using gls what is the gls method tsdata gls tsdata gls estimating time series calculating time series regression with gls method calculating time series regression time series regression using gls how do you calculate gls time series? how to forecast time series how to estimate time series with gls how do i get a time series model estimate using gls gls estimate time series when to use mtr tsdata and ts data how to estimate time series regression what is gls in time series regression gls estimate time series sri tsdata formula for gls model how to find the erorr of time series model using gls