Forecasting market shares from models for sales

Dividing forecasts of brand sales by a forecast of category sales, when the y are generated from brand specific sales-response models, renders biased f orecasts of the brands' market shares. In this note we propose as an altern ative a simulation-based method which results in unbiased forecasts of mark et shares. An application of this forecasting technique to a five brand tun a fish market illustrates its practical relevance. (C) 2001 International I nstitute of Forecasters. Published by Elsevier Science B.V. All rights rese rved.