Mammograms: when and how often?

At what age should we start getting mammograms and how often should we get them? It’s necessary to balance the dangers of ionizing radiation against the benefits of detecting cancer early. Read “Mammography’s Limits are Becoming Clear.”

Currently reading: Outliers

Malcolm Gladwell’s Outliers is a book that makes me think. Using statistics from demographics, education, sport, and individual biographies, he shows that a minor advantage caused by happenstance can translate into an insurmountable advantage years later. The happenstance is often being just a bit older when training or education starts. That accrues extra help and practice time and the snowball is rolling. At the end of the process, a sport or vocation is missing half its potential because half the population was filtered out at the start by happenstance.

Gladwell also maintains that expertise comes from practice and a lot of the difference in outcomes is derived from differential opportunity to amass the 10,000 hours of practising needed. He cites musicians in general, the Beatles, and Steve Jobs. He points out that most American self-made millionaires were born in a span of only nine years, 1831 – 1840, and that today’s most successful computer startup firms had founders with an even narrower range, 1953 – 1956. If you were older, you were settled into a different career and if you were younger, it was too late.

Another point he made was that there’s some level that’s good enough, after which more intelligence makes no difference to professional outcomes.

I’m only half-way through the book. Perhaps he’s cherry-picking his examples but it is thought-provoking.

• Book review on Google
• Discussion on Gladwell’s website. “In the case of Outliers, the book grew out a frustration I found myself having with the way we explain the careers of really successful people. You know how you hear someone say of Bill Gates or some rock star or some other outlier—”they’re really smart,” or “they’re really ambitious?’ Well, I know lots of people who are really smart and really ambitious, and they aren’t worth 60 billion dollars. It struck me that our understanding of success was really crude—and there was an opportunity to dig down and come up with a better set of explanations.”
• Review on Goodreads
• Wikipedia article
• Book on Amazon.com

What are the odds?

Creationists, or anti-evolutionists, are fond of declaring that the odds against evolution or of abiogenesis are great, so great as to make it almost impossible. Some say that the odds of the simplest organism forming “by chance” are 1 in 10^340,000,000. Of course, to get those numbers they have to ignore the facts about how chemical changes occur or how evolution occurs and assume that everything happens at once, like an egg smash played in reverse.

However, scientists can play the numbers game, too. Doug Theobald has used phylogenetic software to calculate the odds that a group of proteins occurring in all life originated independently. You can read about it on Pharyngula.

…take a small set of known, conserved proteins that are shared in all organisms, not restricting ourselves to one kingdom or one phylum, but grabbing them all. In this paper, that data set consists of 23 proteins from 12 taxa in the Big Three domains: Bacteria, Archaea, and Eukarya. Then set up many different models to explain the relationships of these species. … And the winner is…common ancestry, with one branching tree!

Theobald distills it down to just the odds that bacteria have an independent origin from Archaea and eukaryotes:

But, based on the new analysis, the odds of that are “just astronomically enormous,” he said. “The number’s so big, it’s kind of silly to say it”–1 in 10 to the 2,680th power, or 10 followed by 2,680 zeros.

One in 10²⁶⁸⁰…

What causes third-trimester abortions?

After the murder of abortion provider George Tiller for doing third-trimester abortions, there were a lot of hysterical accusations about the number of abortions he did and the reasons for them. I looked for solid research on the reasons. I read the personal experiences of people who had to face third-trimester abortions. They wanted to have a baby, but genetic or developmental errors intervened. Given the frequency of these defects, Dr. Tiller probably did about a 100 – 200 a year, but that’s just a rough estimate on my part. It’s certain he didn’t do 60,000, which would keep him working feverishly every day for two lifetimes.

The reasons they gave were basically the same as those I found in a research paper from 1999, on second-trimester and third-trimester abortions at one hospital over several years. Only “singletons” were studied, so none of the fetuses were conjoined twins, which is another way that a fetus can be non-viable. About 2/3 were done in the second trimester and 1/3 in the third trimester. The reasons for a third-trimester abortion were:

* In 40%, an earlier test indicated that a defect existed but not how serious it was. Doctors delayed and re-tested to see if the defect was serious enough to be life-threatening. Some genetic conditions can be mild or severe, so to prevent unnecessary abortions the doctors waited.
* In 37%, an earlier test failed to find the serious defects that showed up later.
* In 18%, a diagnosis for this kind of defect can’t be made until the third trimester. This often seems to include anencephaly, a fatal birth defect.
* And in the remaining 5%, doctors or parents delayed the decision to abort. I correlated this with what I’ve read about doctors ordering yet another another test to make sure, waiting for a referral, parents not able to believe the news, having hysterics and going home, and praying for a miracle.

Reference:
Dommergues M, Benachi A, Benifla JL, des Noëttes R, Dumez Y., British Journal of Obstetrical Gynaecology, 1999 Apr;106(4):297-303. The reasons for termination of pregnancy in the third trimester. PubMed ID: 10426234.

If third-trimester abortions are outlawed, some parents may choose earlier abortions when it’s not certain they are needed.

Some critics mentioned club foot as a reason for abortion. Club foot means that at least one foot is turned in. It is not a reason for abortion, but it is a warning to screen very carefully for other health problems. The same goes for other deformities of the digits or limbs. Club foot is associated with spina bifida and anencephaly and other birth defects, some of them fatal.

One defect that can be missed at the second-trimester scan is anencephaly, in which the brain fails to develop. It is uniformly fatal, often before or during birth.

Anencephaly, view of back of head

Great Global Warming Swindle exposed

This isn’t new, but someone has done a very nice job of dissecting a British documentary and showing its misinformation, fraudulent graphs, and false data: Great Global Warming Swindle complaint to the U.K. Office of Communications.

Among the breeches of the broadcasting code were misrepresenting the purpose of the film when interviewing; falsification of graphs or data or quotations from reports; selectively editing interviews to misrepresent the positions of the interviewees; making serious (and often false) allegations without giving those accused an opportunity to respond; use of logical fallacies “straw man,” “ad hominem,” and “non sequitur” by a public broadcaster; recycling of long-discredited myths; combining interview and narrator statements to make a misleading narrative; using data that is thirty years out of date; and making false statements.

Left, misrepresented data; right, actual global warming

Science papers online

Here’s a boost to research: more than half a million science papers online at arXiv. Their content description lists these subjects:

• Physics
• Mathematics
• Computer Science
• Quantitative Biology
• Quantitative Finance
• Statistics

In other words, these are papers that deal with mathematics and with quantifying results.

It’s one of the ways in which the Web makes science much more accessible to us.

Hat tip to Blake Stacey at Science After Sunclipse.

Sturgeon’s Law anticipated

The second Sturgeon’s Law, or Sturgeon’s Revelation, is “Ninety percent of everything is crud.”

However, as Ecclesiastes says, “There is nothing new under the sun.” So I shouldn’t have been surprised to find this quote:

Nine-tenths of the people were created so
you would want to be with the other tenth.
— Horace Walpole, 1717 – 1797

Thanks to Mark Leeper, who supplied this for The MT Void Vol. 27, No. 36.