Reducing the influence of anecdotal reasoning on people's health care decisions: is a picture worth a thousand statistics?
BACKGROUND
People's treatment decisions are often influenced by anecdotal rather than statistical information. This can lead to patients making decisions based on others' experiences rather than on evidence-based medicine.


OBJECTIVE
. To test whether the use of a quiz or pictograph decreases people's reliance on anecdotal information.


METHODS
. Two cross-sectional survey studies using hypothetical scenarios. Participants read a scenario describing angina and indicated a preference for either bypass surgery or balloon angioplasty. The cure rate of both treatments was presented using prose, a pictograph, a quiz, or a pictograph and quiz combination. Participants read anecdotes from hypothetical patients who described the outcome of their treatment; the number of successful anecdotes was either representative or unrepresentative of the cure rates. Setting and Participants. Prospective jurors at the Philadelphia County Courthouse and travelers at the Detroit-Wayne County Metropolitan Airport. Measurements. Proportion of respondents preferring bypass over balloon angioplasty.


RESULTS
. In study 1, when statistical information was presented in prose, treatment choices were influenced by anecdotes, with 41% of participants choosing bypass when the anecdotes were representative and only 20% choosing it when the anecdotes were unrepresentative (x(2) = 14.40, P < 0.001). When statistics were reinforced with the pictograph and quiz, anecdotes had no significant influence on treatment decisions (38% choosing bypass when anecdotes were representative v. 44% when unrepresentative, x(2) = 1.08, P > 0.20). In study 2, the tradeoff quiz did not reduce the impact of the anecdotes (27% v. 28% choosing bypass after receiving or not receiving the quiz, x(2) < 1, P > 0.20). However, the pictograph significantly reduced the impact of anecdotes, with 27% choosing bypass after receiving no pictograph and 40% choosing bypass after receiving a pictograph (x(2) = 6.44, P < 0.001).


CONCLUSIONS
. Presenting statistical information using a pictograph can reduce the undue influence of anecdotal reasoning on treatment choices.
Fagerlin
Angela
A
VA Health Services Research & Development Center of Excellence, VA Ann Arbor Healthcare System, Ann Arbor, MI 48109-0429, USA. fagerlin@umich.edu
Wang
Catharine
C
Ubel
Peter A
PA
D000328:Adult; D000368:Aged; D000787:Angina Pectoris / Q000601:surgery; D000800:Angioplasty, Balloon; D001294:Attitude to Health; D001026:Coronary Artery Bypass; D003657:Decision Making; D005260:Female; D006801:Humans; D008297:Male; D008824:Michigan; D008875:Middle Aged; D015143:Philadelphia; D013223:Statistics as Topic; D011795:Surveys and Questionnaires