Crystal Ball uses Holt’s double exponential smoothing formula as follows:
(Initialization) L1 = Y1, T1 = 0
Level: Lt = α * Yt + (1 – α) * (Lt-1 + Tt-1)
Trend: Tt = β * (Lt – Lt-1) + (1 – β) * Tt-1
Fit: Ft = α * Yt-1 + (1 – α) * Ft-1
Forecast for period m: Ft+m = Lt + m*Tt
Note: | First fit is available from period 2. |