But It Can’t Settle Policy
You have no history of breast cancer, nor worrisome symptoms. Should you have a mammogram?
canada goose uk outlet If you follow the American Cancer Society’s recommendation, the answer is “yes”: You should begin routine mammography screening for breast cancer at age 45. Preventive Services Task Force recommendation, the answer is “no”: You should probably wait another 5 years. canada goose uk outlet
Answering this question goes well beyond the evidence. It’s not just that the evidence is imperfect (though it always is). Rather, it’s that turning evidence into policy requires more than empirical facts; it also depends on values. In this case, recommendations could differ depending on how much value is placed canada goose premium outlet on avoiding “false alarms” cases in which a mammogram leads to subsequent tests or treatments that are ultimately unnecessary versus the value of preventing “misses,” or cases in which a cancer that could have been caught by routine mammography slips by.
buy canada goose jacket Christie Aschwanden discusses this example in a nice post canada goose outlet store uk at FiveThirtyEight. The headline summarizes the key lesson: “Science Won’t Settle The Mammogram Debate.” buy canada goose jacket
But the lesson is a much canada goose outlet sale more general one: Science can (and should) inform most policy decisions, but science, on its own, won’t settle policy. The need to trade off different kinds of errors is one pervasive reason why. Science can quantify the relative risks, but it can’t ultimately answer the question of how much we value avoiding a false alarm relative to preventing a miss.
Canada Goose Jackets Consider an example from another domain: eyewitness identification. Canada Goose Jackets
You unwittingly observe a crime, and you get a fleeting glimpse of the perpetrator. The police later show you a photograph of a suspect: Is it the person you saw?
buy canada goose jacket cheap There are two different ways you might go wrong. First, you could wrongly say “yes,” because the person in canada goose outlet online uk the photograph is not the one you saw. If you make this kind of error a false alarm you risk contributing to the conviction of an innocent person. But if you wrongly say “no” a miss a dangerous criminal could go free. buy canada goose jacket cheap
canada goose coats on sale How confident do you need to be in your judgment before you’re willing to say “yes”? The answer depends not only on the quality of your memory, canada goose outlet but also on how you weight the risk of a false alarm against the hazards of a miss. canada goose coats on sale
Canada Goose Outlet Decisions about how to weight these errors of eyewitness identification arise at a policy level as well, not only for individuals tasked with making identifications. For instance, there’s currently some debate about whether it’s best www.yokosukabase.com to present eyewitnesses with a lineup, in which several individuals are visible simultaneously, or to have them make yes/no decisions about individuals sequentially. Although eyewitnesses’ total accuracy is likely similar across these presentation modes, the kinds of errors they’re more likely to make may differ. If that’s right, policy decisions about which presentation style to adopt will implicitly value one type of error avoidance over the other. Canada Goose Outlet
More mundane examples abound.
canada goose store The weather forecast on Monday morning predicts a 20 percent chance of rain. Do you take an umbrella? Avery, who hates to carry an umbrella unnecessarily and who doesn’t really mind getting wet, doesn’t bother. Blake, who loves accessories and dry clothes, opts for an umbrella and a raincoat. Avery and Blake don’t disagree about the probability of rain; instead, they weight the costs of different errors differently. canada goose store
canada goose uk black friday Carter and Dakota decide to bake chocolate chip cookies. When the timer goes off after a few minutes, they peer at the cookies uncertainly. Should they pull them out now and risk having a batch of under baked cookies? Or wait another five minutes and, instead, risk a batch of over baked cookies? Carter, who hates cookies to be doughy, opts for waiting. canada goose outlet store montreal Dakota, who hates cookies that are dry, wants to take them out now. They don’t disagree about the relative risks; they disagree about which risk under or over baking is more grievous. canada goose uk black friday
A final example comes from science itself.
When scientists test hypotheses using statistical tests, they typically decide on some value beyond which a test is considered statistically “significant.” For instance, the norm in psychology is to consider a statistical test significant when it yields a p value below 0.05, which means that the probability of seeing results at canada goose outlet near me least canada goose outlet miami as extreme due to chance is less than 5 percent. Psychology could become more conservative, however, by lowering this critical threshold, making it less likely canada goose outlet online that the field reports false alarms: “significant” results that are just statistical flukes. But doing so would also increase the probability of misses: failures to recognize real effects. Scientific “policies” just like policies in other domains effectively value some kinds of error avoidance over others.
Canada Goose Coats On Sale Recognizing that science can’t settle policy doesn’t open the floodgates to skepticism or radical relativism. It doesn’t mean we should give up on evidence based policy, or that “anything goes.” Instead, it invites us to recognize our values and subject them to scrutiny. Canada Goose Coats On Sale
It’s not enough to have canada goose outlet online store review solid evidence; we also need solid values. And that requires careful science, but also careful thought.