Mappings (Choice to Welfare)

Understanding “Mappings”: From Choice to Welfare

Some tasks are easy, like choosing a flavor of ice cream; other tasks are hard, like choosing a medical treatment. Consider, for example, an ice cream shop where the varieties differ only in flavor, not calories or other nutritional content. Selecting which ice cream to eat is merely a matter of choosing the one that tastes best. If all of the flavors are familiar, most people will be able to predict with considerable accuracy the relation between their choice and their ultimate consumption experience. Call this relation between choice and welfare a mapping. Even if there are some exotic flavors, the ice cream store can solve the mapping problem by offering a free taste.

Choosing among treatments for some disease is quite another matter. Suppose you are told that you have been diagnosed with early-stage prostate cancer and must choose among three options: surgery, radiation, and “watchful waiting,” which means doing nothing for now. Watchful waiting can be an attractive option because prostate cancer usually progresses slowly. Each of these options comes with a complex set of possible outcomes regarding side effects of treatment, quality of life, length of life, and so forth. Comparing the options involves making such trade-offs as the following: Would I (hypothetically) be willing to risk a one-third chance of impotence or incontinence in order to increase my life expectancy by about three years? This is a hard decision on two levels. First, the patient is unlikely to know the data about the relative risks and benefits of each option, and second, he may have difficulty forecasting what life would be like if he were incontinent.

And here are two scary facts about this scenario. First, many patients are asked to decide which course of action to take in the very meeting at which their doctor breaks the bad news about the diagnosis. Second, the treatment option they choose depends strongly on the type of doctor they see.12 (Some specialize in surgery, others in radiation. None specialize in watchful waiting. Guess which option we suspect might be underutilized.) Note that in an attempt to increase the number of patients who elect watchful waiting, it has been reframed as “active surveillance,” which sounds less passive.

The comparison between ice cream and treatment options illustrates the concept of mapping. A good system of choice architecture helps people to improve their ability to map choices onto outcomes and hence to select options that will make them better off. One way to do this is to make the information about various options more comprehensible, by transforming numerical information into units that translate more readily into actual use. If I am buying apples to make into apple cider, it helps to know the rule of thumb that it takes three apples to make one glass of cider. If you are told that a tire’s safety rating is 4 on a scale of 1 to 10, it would be valuable to give you a sense of what that means, in terms of what actually matters to you. (And yes, this example comes from actual deliberations within the U.S. government, about how best to convey the safety ratings of tires.)