Electronic Companion to: A Bayesian Model for Sales Forecasting at Sun Microsystems

There is a wealth of literature documenting the biases and errors associated with judgmentbased forecasting—c.f. (McGlothlin 1956, Tversky and Kahneman 1974, Wright and Ayton 1986, Bolger and Harvey 1998), for example. Mentzer and Bienstock (1998) and Tyebjee (1987) point out that in addition to these problems, judgmental sales forecasts could be distorted by other factors, such as organizational pressures. Many researchers and practitioners have sought to combine judgmental and statistical forecasting techniques. Broadly speaking, such efforts may be categorized under the headings: Adjustment, combination, correction, judgmental bootstrapping, and Bayesian methods.