Notation | Description |

| Forecast at the beginning of moth t of demand in month t |

d | Demand in month t |

| Forecast in month t of number of months between consecutive positive demands (CR, SBA) |

k | Number of months since the last positive demand at the beginning of month t (CR, SBA) |

| Forecast of demand in month t, provided this demand is positive (CR, SBA, TSB) |

| Forecast of the probability of a positive demand in month t (TSB) |

p | Indicator variable that indicates whether or not there is a positive demand in & month t (TSB) |

α, β | Smoothing constants (0 ≤ α, β ≤ 1) |