Originally published in 1989, this volume carefully catalogues and classifies the effect of bias on quantitative judgments. Each bias is described by model and examples of this bias are given. The examples include both theoretical investigations carried out in the laboratory to study bias and practical illustrations. They are accompanied by a discussion of methods of avoiding bias, where this is possible. An early look into this now widely recognised subject, this book was an invaluable resource for investigators and practitioners in applied science at the time.