In the STEPAR method, PROC FORECAST first fits a time trend model to the series and takes the difference between each value and the estimated trend. (This process is called detrending.) Then, the ...

Crane, D. B., and James R. Crotty. "A Two-Stage Forecasting Model: Exponential Smoothing and Multiple Regression." Management Science 13, no. 8 (April 1966).

The ARIMA model equivalency to the additive version of Winters method is the ARIMA(0,1,p+1)(0,1,0) p model The moving-average form of the equation is For the additive version of Winters method (see ...