TSB (Teunter, Syntetos and Babai) is a new method proposed in 2011, the method replace the demand interval by demand probability which is updated every period. The reason for this is the Croston’s method only update demand when it occur, however in real life there are plenty of cases with many zero demands, therefore, the result of forecast will be unsuitable for estimating the risk of obsolescence because of the outdated information.
In TSB method, the Dt represent the demand occurrence indicator for period t, so :