A QUIBBLE ABOUT RANDOM PROCESSES. David Adler in his article says: “But we are also fooled by nearly random processes that look random, even if they aren’t, because the differences are too subtle for us to notice.” Kids, I would think of the results of an “ordinary person” flipping a coin as still being a random process—only the mean of the random process is .51 rather than .50.
Archive for July, 2009
A QUIBBLE ABOUT RANDOM PROCESSES.
Friday, July 31st, 2009FLIPPING COINS WITH A BETTER THAN 50/50 PROBABILITY OF WINNING.
Friday, July 31st, 2009FLIPPING COINS WITH A BETTER THAN 50/50 PROBABILITY OF WINNING. Kids, flipping a fair coin is often used as an example of a random process, with a 50% probability of the coin coming up heads. This article, based on David Adler’s book SNAP JUDGMENT, reports on a paper by three Stanford mathematicians which concludes that if a coin is heads up before it is flipped, the probability of a coin coming up heads after it is flipped by an ordinary person is at least 51%–not 50%. The paper is really about the physics of coin flipping. When an “ordinary person” flips a coin, the coin tumbles, but it also spins —Adler compares the spin to a pizza being twirled. The spin is what causes the deviations from 50/50. The paper has photos of a coin-tossing machine which, after adjustments, will flip a coin so that it will always come up heads if it starts out heads up. I used the phrase “flipped by an ordinary person” in the earlier sentence because there are magicians who can make a coin come up the same way it started every time, just as the coin-flipping machine does. And the magician’s flip will look like the flip of an “ordinary person.” The article points out that if the initial position of the coin is random, then the coin is equally likely to come up heads or tails and points out: “We have friends who preface a coin toss by vigorously shaking the coin between their cupped hands.” two kinds of expertise contributed to the paper. Adler tells us that one of the authors of the article was a professional magician before becoming a mathematician.
COMPARING EMERGENCY MEDICAL SERVICES.
Thursday, July 30th, 2009COMPARING EMERGENCY MEDICAL SERVICES. The David Brown article concludes by identifying an area where more reductions in heart disease deaths can be obtained: “A big focus in cardiology right now is to get more heart attack victims to the hospital. Today, about 40 percent of them delay longer than six hours, by which time optimal treatment isn’t possible.” Some of that improvement would have to come from educating the public. But USAToday, which has always done a wonderful job of providing cross-sectional data (such as state by state breakdown) on important issues, had a wonderful series about emergency medical service responses in fifty major cities. Here is part of the series. Another part of the series explained how Seattle has outperformed other cities by coordinating the actions of firefighters and ambulance crews and by “meticulously measuring the performance of the system, chiefly by monitoring sudden cardiac arrest survival.” This part of the series tells how Boston went from saving 14% of cardiac arrest victims in 1993 to saving 40%. I think that there should be a lot more of this kind of comparative determination of best practices.
SHOULD EVERYONE CARRY ASPIRIN?
Wednesday, July 29th, 2009SHOULD EVERYONE CARRY ASPIRIN? There is a considerable effort being made to make defribillators more available in public spaces, such as airports, which seems to be a good idea. David Brown’s article suggests another one. The article begins: “Two decades ago, a famous clinical experiment showed that if a patient in the throes of a heart attack chewed and swallowed an aspirin tablet, the risk of dying fell from 13.2 percent to 10.2 percent.” Why hasn’t there been a campaign to have everybody carry a couple aspirin, just in case somebody in the vicinity has a heart attack?
THE FIGHT AGAINST HEART DISEASE—”EXTREMELY EXPENSIVE AND WILDLY SUCCESSFUL.”
Tuesday, July 28th, 2009THE FIGHT AGAINST HEART DISEASE—”EXTREMELY EXPENSIVE AND WILDLY SUCCESSFUL.” I argued here that it is wrong to talk about the increase in health care costs without taking into consideration the improvements that those higher costs are achieving. The quote in the caption is from a wonderful article in the Washington Post by David Brown that analyzes some of the improvements. Here are the numbers:
“In the 1960s, the chance of dying in the days immediately after a heart attack was 30 to 40 percent. In 1975, it was 27 percent. In 1984, it was 19 percent. In 1994, it was about 10 percent. Today, it’s about 6 percent.
Over the same period, the charges for treating a heart attack marched steadily upward, from about $5,700 in 1977 to $54,400 in 2007 (without adjusting for inflation).”
The death rate from heart disease is less than a third of what it was in 1970. About half of the decline in that death rate since 1980 is due to improvements in medical care and about half to a lower risk profile—”less smoking, lower cholesterol, better blood pressure.” I note that lower cholesterol and better blood pressure may partly be due to better drugs.
GREASE.
Monday, July 27th, 2009GREASE. Kids, the musical comedy/movie GREASE has always seemed to be about my high school. There were over 4000 students at York Community High School when I was there. There was a socioeconomic split that I was aware of more in retrospect. The students came from Villa Park and Elmhurst, and Villa Park was more of a blue collar town, perhaps because of the Ovaltine plant. I did notice that a lot of the Villa Park kids who were assigned to college prep classes as freshmen were taking a different track by sophomore year. And I couldn’t miss the greaser style (as in GREASE). Kids from both towns adopted the style, but none of those who did were in the college prep classes. They were called “hoods” and the style was called “hoody.” (It’s important that the words were pronounced to rhyme with “food” and “foody.”)
OVALTINE.
Sunday, July 26th, 2009OVALTINE. Vikki Oritz, who wrote the article on the Roarin’ Elgin that I posted on here, has an article on the Ovaltine plant in Villa Park, Illinois, which was also part of my youth. Villa Park was next to Elmhurst, Illinois, where I grew up. I learned that the Ovaltine plant, where the chocolate drink was manufactured, had closed in 1987. The plant had been located in Villa Park partly because of the access to two railroads (the Northwestern and the Roarin’ Elgin). I had friends who worked at the Ovaltine plant in the summers, and they told me that they were told the jobs were dangerous. The plant was quite hot, and there were stories about an unfortunate worker who had been overcome by heat and fallen into chocolate powder and died. I could never decide whether the stories were true.
HOW THE ROMANS BUILT ARCHES AND DOMES.
Saturday, July 25th, 2009HOW THE ROMANS BUILT ARCHES AND DOMES. This wikipedia article describes the traditional way that Roman arches were constructed: “An arch requires all of its elements to hold it together, raising the question of how an arch is constructed. One answer is to build a frame (historically, of wood) which exactly follows the form of the underside of the arch.” A similar technique was apparently used for domes. The circular part of the upper dome of the Pantheon, according to this article, “was likely placed by using wooden scaffolding.” One of the secrets of the Pantheon is that lighter stone was used at the top: “The upper dome above the step-rings (the top 30 feet/9.1 m) is concrete comprising about 9 inch lumps of light tufa and porous volcanic slag in alternating layers bonded with mortar.” Apparently we can now build a dizzyingly high arch without scaffolding or a framework underneath.
CONSTRUCTING AN ARCH.
Saturday, July 25th, 2009CONSTRUCTING AN ARCH. Henry Nejako sent me this slide show of the ongoing construction of the Hoover Dam Bypass, also known as the Colorado River Bridge with the caption “Acrophobiacs beware.” In case the New York Times link goes down, here is a link to a slide show at the site of Jamey Stillings, who took the wonderful pictures. The warning to acrophobiacs is apt. I have a physical reaction to the photographs. Apparently a modern arch can be built by simply building each side up until they join.
HOW DO BRIGHT RED MALE CARDINALS SURVIVE?
Friday, July 24th, 2009HOW DO BRIGHT RED MALE CARDINALS SURVIVE? Jack Sanders, who writes a wonderful column on birds in the Darien Times, asked this question. It’s the kind of question that scientists ask and that never occur to me. As with many evolutionary questions, where experiments are hard to do, the proposed answers are cautiously stated. It is agreed that the male cardinal’s color probably evolved because of the advantage to attracting female cardinals. But what about attracting hawks? Hawks can see red. The article has a number of proposed explanations. 1. Hawks see differently than we do, including seeing in the ultraviolet ranges so that cardinals may not stand out to a hawk. 2. The green of a forest may absorb red light so that cardinals don’t stand out against a green background. 3. There are more cardinals than hawks so that enough cardinals may survive for evolutionary purposes. 4. While hawks can see red, their favored prey has more muted colors so that hawks may focus on birds with muted colors. 5. Cardinals spend a lot of time hidden in foliage.
