TY - JOUR
T1 - The 1-in-X effect on the subjective assessment of medical probabilities
AU - Pighin, Stefania
AU - Savadori, Lucia
AU - Barilli, Elisa
AU - Cremonesi, Laura
AU - Ferrari, Maurizio
AU - Bonnefon, Jean François
PY - 2011/9
Y1 - 2011/9
N2 - Among numerical formats available to express probability, ratios are extensively used in risk communication, perhaps because of the health professional's intuitive sense of their clarity and simplicity. Moreover, health professionals, in the attempt to make the data more meaningful, tend to prefer proportions with a numerator of 1 and shifting denominators (e.g., 1 in 200) rather than equivalent rates of disease per unit of population exposed to the threat (e.g., 5 in 1000). However, in a series of 7 experiments, it is shown that individual subjective assessments of the same probability presented through proportions rather than rates vary significantly. A 1-in-X format (e.g., 1 in 200) is subjectively perceived as bigger and more alarming than an N-in-X*N format (e.g., 5 in 1000). The 1-in-X effect generalizes to different populations, probabilities, and medical conditions. Further-more, the effect is not attenuated by a communicative intervention (verbal analogy), but it disappears with an icon array visual aid.
AB - Among numerical formats available to express probability, ratios are extensively used in risk communication, perhaps because of the health professional's intuitive sense of their clarity and simplicity. Moreover, health professionals, in the attempt to make the data more meaningful, tend to prefer proportions with a numerator of 1 and shifting denominators (e.g., 1 in 200) rather than equivalent rates of disease per unit of population exposed to the threat (e.g., 5 in 1000). However, in a series of 7 experiments, it is shown that individual subjective assessments of the same probability presented through proportions rather than rates vary significantly. A 1-in-X format (e.g., 1 in 200) is subjectively perceived as bigger and more alarming than an N-in-X*N format (e.g., 5 in 1000). The 1-in-X effect generalizes to different populations, probabilities, and medical conditions. Further-more, the effect is not attenuated by a communicative intervention (verbal analogy), but it disappears with an icon array visual aid.
KW - numerical risk format
KW - probability assessment
KW - risk communication
UR - http://www.scopus.com/inward/record.url?scp=80052826932&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=80052826932&partnerID=8YFLogxK
U2 - 10.1177/0272989X11403490
DO - 10.1177/0272989X11403490
M3 - Article
C2 - 21512187
AN - SCOPUS:80052826932
VL - 31
SP - 721
EP - 729
JO - Medical Decision Making
JF - Medical Decision Making
SN - 0272-989X
IS - 5
ER -