A method of quantifying the strength of a person's opinion on a topic of interest. The idea is that a series of k related yes/no questions in a questionnaire may be ordered in the sense that when the questions have been arranged in the appropriate order, an individual who answers ‘Yes’ to question j (<k) will probably answer ‘Yes’ to questions j + 1, j + 2,…, k. For example, a Guttman scale is formed by the series of questions asking whether an individual deserves the death penalty for killing another when the killing was

1. 1. by accident;

2. 2. in self-defence;

3. 3. in the heat of the moment;

4. 4. premeditated.

Usually the ordering of the questions will be less obvious.