![]() Bradford Hill considered other factors that had changed during that period, including improvements in diagnostic methods, increases in air pollution, and differences in occupation. Similarly, the incidence of lung cancer, particularly in men, increased dramatically between the 1920s and the 1940s. The prototype blue zones showed how natural experiments inform public health-in this case, to promote longevity. Video: Physical activity is one of nine aspects of the Blue Zone lifestyle. At first Morris’ findings, published in 1953, met with skepticism. Similarly, mail carriers enjoyed considerably better health than more sedentary postal workers or telephone workers. Comparing health data from 31,000 transit workers showed dramatically better coronary health for those whose work entailed physical activity than those doing sedentary work. It was a miserable existence.-“How London bus drivers changed the world,” The Economist, 7 September 2023īus conductors repeatedly climbed up and down the stairs on the double-decker buses, while drivers sat most of the time. They also suffered disproportionately from various diseases, died young and featured in novels by D.H. Navvies, miners and farm labourers did physical exercise by the spade-load. Some even felt that “too much physical activity was a bad thing for your health”. The idea that health and exercise were linked “wasn’t the accepted fact that we know today”, says Nick Wareham, a professor of epidemiology at Cambridge University. Jeremiah Morris looked for clues by studying bus drivers and conductors and postal- and telephone workers. In the 1940s, doctors in wealthy countries became concerned about the increasing incidence of heart disease. Natural experiments inform public health Blue zone studies have shown that both physical activity and relationships promote longevity. That allowed him to control for a recession that affected both areas while the experiment was going on. For example, in his work on the effects of a minimum wage increase, he surveyed two adjacent geographic areas in New Jersey and Pennsylvania before and after the increase took effect in New Jersey. Other changes could take place during the same period, and it may not be possible to deconvolute all their effects. When examining changes in public policy, it’s not enough to look at the same group before and after the change. Together, their work helps us extract the right lessons from natural experiments.Ĭard’s methodology provides more than one control group. Angrist and Imbens developed a mathematical framework for determining cause and effect when it’s not possible to use strict scientific methods. Despite being decades old, Card’s findings speak to some of today’s “hot button” issues. The 2021 Nobel Prize in economics went to David Card, Joshua Angrist, and Guido Imbens. It’s important to interpret experience with an open mind and be as objective as possible. That is, we interpret our observations as supporting what we already believe. What we take away from experience is subject to confirmation bias. ![]() Some people will hold onto it no matter how much new information comes out later-they simply won’t change their minds. And once that false conclusion is out there, it takes on a life of its own. But it’s more likely to lead to a false conclusion. That may get us the right answer by pure luck. On the other hand, if we consider a few instances and figure out what they have in common, we’re equating anecdotes with data. But if they keep doing the same thing hoping the results will be different, should that be a point of pride? Or if the utility didn’t upgrade the power grid after a catastrophic power outage, should we be surprised when it happens again? When people rebuild after a flood on the same low-lying land, they may talk of resilience or courage. Let’s look at some examples of how natural experiments inform public health. In that case, natural experiments may be the best option. However, some questions don’t lend themselves to that kind of study. Ideally, experiences would lead us to develop hypotheses, which we could test in controlled experiments. Ultimately, survival and flourishing depend on being able to extract the right lessons from experience. Previous posts on this blog have explored learning-or failing to learn-from experience.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |