A New Scale for Assessing Perceptions of Chance

Abstract

Background. Clinicians and researchers often wish to know how patients perceive the likelihoods of health risks. Little work has been done to develop and validate scales and formats to measure perceptions of event probabilities, particularly low probabilities (i.e., 5) than on its linear counterpart (10^-2). Participants' assessments of high-probability events (e.g., chance of catching a cold in the next year) were not affected by the presence of the magnifier. Conclusions. The "1 in x" scale performs poorly and is very difficult for people to use. The magnifier scale and the linear number scale are similar in validity, reliability, and usability. However, only the magnifier scale makes it possible to elicit perceptions in the low-probability range (<1%). Key words: patient perceptions; perception measurement scale. (Med Decis Making 2000;20:298-307)