Weiye Loh's Library tagged Correlation → View Popular, Search in Google

Aug

2011

Trying to Live Forever - NYTimes.com

opinionator.blogs.nytimes.com/...trying-to-live-forever

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Correlation Causation Life Information Overload Health Medicine Science

An article in the May Consumer Reports Health shed some light on this question. It discussed the widely publicized medical study that showed, contrary to expectations, that “raising HDL (good) cholesterol with drugs did nothing to protect against heart attacks.” This, the article said, was surprising because observational studies had shown that people with lower levels of HDL had more heart attacks than those with higher levels of HDL. An observational study, however, shows only a correlation between two variables (e.g., level of HDL and number of heart attacks). The new result came from a randomized clinical study, using one group of patients who receive a given treatment and a “control group” of patients who do not. Unlike an observational study, such a study can show whether or not, for example, higher HDL actually prevents heart attacks. The article went on to emphasize that “we should almost never rely on the results of observational studies, which can only suggest associations with disease but not prove them.”
implicit in most media reports, is that acting on the results of the unreliable observational studies “couldn’t hurt and might help.” This makes sense if I have a medical problem for which there is no reliable remedy. If nothing else has helped my arthritis, insomnia or back pain, it would make perfect sense to try a remedy that will not do serious harm and has some probability of working.
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- But most observational studies concern not remedies for present ills but protection against future ones, and for these cases it is hard to tell if even relatively small costs or risks of harm outweigh the probability of partial protection
- More important, there is a reasonable chance that further observational studies will call into question the one I’m acting on or even
- it would seem preferable to keep healthy by a method that is simple, reliable and doesn’t require constant revision and fine-tuning. We do, after all, have such a method available: simply follow the humdrum standard advice we’ve heard all our lives about eating sensibly, exercising regularly, and having recommended medical tests and exams. Doing this and foregoing the endless calibration of our behavior to the latest research results will be far less stressful, make it more likely that we’ll stick to the method, and allow more time for fulfilling pursuits. From this point of view, the media’s constant updates on the latest observational studies are counterproductive.

Jun

2011

New research an eye opener on cause of myopia - CNN.com

While the belief that prolonged close-up activities like reading and playing computer games cause short sightedness (myopia) is popularly held, new research indicates that a deficiency of sunlight is the true culprit.

Many epidemiological studies have examined the issue of computer, video and television based activities on the eye health of children and have found no association between time spent using digital media and the development of myopia. While it is an intuitive association to make, it simply has not been confirmed. There are some studies that have found an association between the time spent doing near-work activities such as reading and studying, but the results are inconsistent and marginal. There may be an indirect link where children have substituted large amounts of time spent outside with these activities.

edition.cnn.com/...index.html

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Myopia Causation Correlation Science Health

his finding has now been confirmed in a number of other studies from the U.S., Singapore and China. Our hypothesis that the mechanism of the effect of light was mediated by retinal dopamine, a known inhibitor of eye growth whose release is stimulated by light, has also been supported by animal experiments. All of these studies confirm a consistent link between the time spent outdoors and the prevention of myopia, possibly crucially mediated by the at least ten-fold increase in light levels between indoor lighting and being outside. So yes, it is highly likely that there is a direct connection between time spent outside and preventing myopia.
the effect of light on the prevention of the development of myopia may have a threshold effect, that is both the level of light required and the duration of light exposure may need to reach critical amounts before light has its preventive effect.
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- There is no evidence either way that wearing glasses has no effect or hinders the protective effect of sunlight, but this has not been studied systematically.
  
  Young children tend not to routinely wear sunglasses, possibly due to high rates of breakage and general intolerance to wearing glasses. In Australia wearing hats is compulsory at primary school and is encouraged for outdoor activities, but again this seems not to have reduced the protective effect of being outdoors. This may be because even with a hat the level of illumination outside is still so high.
- The differences between countries seem to relate to high levels of myopia in highly urbanized, academically focused countries with an emphasis on early competitive education systems versus low levels in less urbanized and/or countries with more emphasis on learning through play at an early age.
  
  Scandinavian countries seem no more myopic or otherwise than other more southern European countries. In part this may be lifestyle as people with limited sunlight during winter seem to get outside for long hours during the summer which may balance the short available sunlight hours in the winter. However, there is some limited evidence that in these countries, the rate of eye growth advances more in winter and slows in the summer.

Jun

2011

Don’t Miss this Video: “A link between climate change and Joplin tornadoes? Never.” « Climate Denial Crock of the Week

The video takes Bill Mckibben’s recent editorial from the Washington Post, sets it to music and powerful video of the last year’s weather events.

If you haven’t seen the editorial, give that a look first. It starts out -

Caution: It is vitally important not to make connections. When you see pictures of rubble like this week’s shots from Joplin, Mo., you should not wonder: Is this somehow related to the tornado outbreak three weeks ago in Tuscaloosa, Ala., or the enormous outbreak a couple of weeks before that (which, together, comprised the most active April for tornadoes in U.S. history). No, that doesn’t mean a thing.

It is far better to think of these as isolated, unpredictable, discrete events. It is not advisable to try to connect them in your mind with, say, the fires burning across Texas — fires that have burned more of America at this point this year than any wildfires have in previous years. Texas, and adjoining parts of Oklahoma and New Mexico, are drier than they’ve ever been — the drought is worse than that of the Dust Bowl. But do not wonder if they’re somehow connected.

climatecrocks.com/...nge-and-joplin-tornadoes-never

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Climate Science Causation Correlation Uncertainty Rhetoric