forecastingprinciples.com Reviews of Important Papers on Forecasting
Before 1985 Reviews
Review of:

Willem A. Wagenaar and Han Timmers (1979), "The pond-and-duckweed problem: three experiments on the misperception of exponential growth," Acta Psychologica, 43, 239-251.


A recent paper in a series of studies done over several years by the Institute for Perception in the Netherlands. They show how people underestimate exponential growth when presented with historical data, or, in this case visual evidence on the phenomena (presented via a computer display screen). Neither mathematical sophistication no experience with growth processes helped in these judgmental forecasts. Furthermore, the accuracy was worse when the judge used more data. One thing that did help was to convert the problem so as to extrapolate a decreasing function (e/g. forecast population density by using 'square miles per person' rather than 'people per square mile').