Why does framing influence judgment?

Why Does Framing Influence Judgment?
A few years ago, British women were informed that the use Second, there is strong empirical evidence that condi- of the contraceptive pill leads to a 2-fold increase in the tional probabilities (such as sensitivity and specificity) tend risk of thromboembolism. Many stopped taking the pill, to confuse minds, specifically when one wants to infer the which resulted in unwanted pregnancies and abortions.
chances of having a disease after a positive test. The reason If the official statement had instead been that the pill for the confusion again lies in the reference classes, which increases the risk from 1 to 2 in 14,000 women, few women in this case are switched: the sensitivity refers to patients would have been scared. Life and death can depend on how with disease, and specificity to patients without disease.
This second form of confusion can be avoided by using Yet framing itself is not the problem—every piece of information communicated requires a form or frame. The Third, relative risk reduction (RRR) tends to mislead problem is a larger, societal one: the lack of education in patients into overestimating the benefits of therapies and understanding uncertainties and risks, also known as consequently increases their willingness to consent (un- innumeracy. For instance, Sheridan et al. in this issue of informed consent), compared to absolute risk reduction the Journal of General Internal Medicine report that only (AAR) and number needed to treat (NNT). Again, the reason 2% of patients could correctly answer three simple numer- has to do with the reference class. For instance, many acy questions, and that nonwhites, females, and patients health organizations inform women that “mammography without college education misunderstood treatment screening reduces the risk of dying from breast cancer by benefits most.1 Our schools do not teach children the 25%” (RRR). But 25% of what? A woman may assume that mathematics that will be most useful in their future lives: the percentage refers to women like herself who consider statistical thinking. Statistical thinking and the art of screening, and erroneously conclude that 25 of every 100 framing are also absent from most medical curricula and women who participate in screening are saved. In contrast, from continuing education offered to physicians. This when one frames the benefit as “screening reduces the risk omission is costly and irresponsible.
of dying from 4 to 3 in 1,000 women” (an ARR of 1 in 1,000), We could easily help patients, medical students, and physicians, turning their collective innumeracy into insight.
Thus, instead of these three frames that tend to confuse Programs now exist that can achieve this goal with simple patients and physicians—conditional probabilities, single- tools and in short time.2 The know-how is based on two event probabilities, and RRR—we can teach physicians sources: on empirical studies that show when framing has to use frames that foster insight: frequency statements, an effect, as in the excellent review by Moxey et al.3 (this natural frequencies, and absolute risks.2,4 Good hypotheses volume), and, equally important, on theoretical knowledge about why framing influences minds can assist in planning of why framing has an effect. Here are a few examples of new studies and ordering the apparent chaos of positive First, the use of single-event probabilities tends to In contrast, Sheridan et al.1 report that RRR led to confuse patients. Consider the case of a physician who more correct answers by patients than did NNT and ARR.
used to inform his clients of Prozac’s side effects by saying, This surprising result may well be due to their unusual “If you take Prozac, you have a 30% chance of a sexual phrasing of ARR (“treatment A reduces the chance that problem.” When the physician changed his way of commu- you will develop disease Y by 10 per 1,000 persons”), which nicating the risk by using the frequency statement “out of is a hybrid between a single-person and a frequency every 10 patients to whom I prescribe Prozac, 3 to 5 expe- statement, and their equally awkward phrasing of NNT. I rience a sexual problem,” his patients were less anxious and wager that a clearer statement of ARR and NNT will more willing to take Prozac. It turned out that many of increase the understanding of the size of benefit (e.g., ARR: them had originally understood that “something would go “participating in treatment A prevents 10 out of every 1,000 awry in 30% of my sexual encounters.” For single-event persons from getting disease Y”; NNT: “100 patients need versus frequency statements, the mechanism of framing is to undergo treatment A in order to prevent 1 from getting clear. A single-event probability, by definition, does not disease Y”). Transparent wording is the essence of a frame specify the reference class (30% of what?). The physician thought of his patients, but his patients thought of their Finally, there are positive frames (“you have an 80% own sexual encounters. The confusion can be avoided by chance of surviving surgery”) versus negative frames (“you consistently using frequency statements.
have a 20% chance of dying from surgery”). My hypothesis is that they have an effect if patients can reasonably REFERENCES
assume that the physician’s choice of frame conveys addi-tional information, such as dynamic information. For 1. Sheridan SL, Pignone MP, Lewis CL. A randomized comparison of instance, the positive frame can imply that surgery will patients’ understanding of number needed to treat and other increase the survival chance from 0% to 80%, whereas the common risk reduction formats. J Gen Intern Med. 2003;18:884–892.
negative frame suggests that surgery increases the chance 2. Gigerenzer G. Calculated Risks: How to Know When Numbers Deceive You. New York: Simon & Schuster, 2002 (UK edition: Reck- Understanding when and why framing has an effect oning with Risk: Learning to Live with Uncertainty. London: Penguin is essential for informed consent and shared decision mak- ing. It is high time to enter this knowledge into the curricula 3. Moxey A, O’Connell D, McGettigan P, Henry D. Describing treatment effects to patients: how they are expressed makes a difference. J Gen of medical schools.— Gerd Gigerenzer, MD, Center for
Adaptive Behavior and Cognition, Max Planck Institute for 4. Hoffrage U, Lindsey S, Hertwig R, Gigerenzer G. Communicating Human Development, Berlin, Germany. statistical information. Science. 2000;290:2261–2.

Source: http://library.mpib-berlin.mpg.de/ft/gg/GG_Why_2003.pdf