A fascinating book on statistics in the social sciences, by Judith M. Tanur and six other editors, Statistics: A Guide to the Unknown (Holden-Day, 2nd ed. 1978), discusses troubles when people estimate demand by collecting survey data. Think of all the surveys that ask general counsel about the likelihood of their purchasing software or services, such as document management or consulting, in the coming 12 months. (See my post of Oct., 17, 2005 on the plethora of law-department surveys.)
The statistics book states: “Research literature abounds with examples of gross discrepancies between stated purchase intentions and subsequent purchasing behavior.” Some of the inaccuracy springs from the desire of survey respondents to feel in charge and therefore to say, “Yes, we plan to act.” Sometimes the “Yes” strokes the person’s ego. And often people just do not think through how difficult it will be to actually carry out the purchase they say they will make.
This all means that predictions about law departments and how they will manage their purchase in the future remain quite suspect.