Dividing forecasts of brand sales by a forecast of category sales, when they are generated from brand specific sales-response models, renders biased forecasts of the brands' market shares. In this paper we therefore propose an easy-to-apply simulation-based method which results in unbiased forecasts of the market shares. An illustration for five tuna fish brands emphasizes the practical relevance of the advocated method.

forecasting, market shares, sales models
Forecasting and Other Model Applications (jel C53), Business Administration and Business Economics; Marketing; Accounting (jel M), Marketing (jel M31)
Erasmus Research Institute of Management
ERIM Report Series Research in Management
Copyright 2000, D. Fok, P.H.P.F. Franses, This report in the ERIM Report Series Research in Management is intended as a means to communicate the results of recent research to academic colleagues and other interested parties. All reports are considered as preliminary and subject to possibly major revisions. This applies equally to opinions expressed, theories developed, and data used. Therefore, comments and suggestions are welcome and should be directed to the authors.
Erasmus Research Institute of Management

Fok, D, & Franses, Ph.H.B.F. (2000). Forecasting Market Shares from Models for Sales (No. ERS-2000-03-MKT). ERIM Report Series Research in Management. Erasmus Research Institute of Management. Retrieved from http://hdl.handle.net/1765/12