Category: Science

Does grandpa matter?

Even fathers with only one wife provided no [longevity] benefit to their grandchildren, a finding supported by previous research.

That is based on a study of Finnish church data from the 18th and 19th centuries.  The thrust of the entire piece is the claim that polygamous men will live longer than monogamous men.  But note, all you Lotharios out there, this result is correlated with actual [multiple] marriage, not running around in bars and the like.

Ways that sheep can die

Getting stuck on their backs and dying of suffocation
Attacked by flies
Eaten by maggots
Being attacked by dogs or any other living creature
Being frightened into a heart attack by imagining the dog is going to attack, even though it is not
Drowning (Are we surprised sheep cannot swim?)
Suffocating in snow (surprisingly common)
Hoof infections that poison the blood
Almost exploding with grass because they have eaten too much and are unable to pass wind
If they get too hot
If they get too cold

That’s from Marti Leimbach and I wonder how many sheep die of old age.  With that, it is time to leave Santiago and return home.

Bold claims about time asymmetry

…given self-indication we should expect to be in a
finite-probability universe with nearly the max possible number of
observer-moment slots.  Such universes seem large enough to have at
least one inflation origin, which then implies at least one (and
perhaps infinitely many) large regions of time-asymmetry like what we
see around us.  And if, as it seems, most observer-moments in such universes are in
such regions, then we have explained why we see what we see.

That’s from Robin Hanson, one of the least evil people I have met.  I do not have the background to judge this claim but it makes sense to me.  The question is whether you are willing to bite the bullet when you realize the other implications of what Robin is postulating, namely that you start dealing with expected values of infinity, most of all in ethics

By the way, via Andrew Sullivan, here is new evidence for dark energy.

Please solve for the equilibrium

That’s what some environmentalists said they feared when Planktos, a
California-based concern, announced it would embark on a private effort
to fertilize part of the South Atlantic with iron, in hopes of
producing carbon-absorbing plankton blooms that the company could
market as carbon offsets. Countries bound by the London Convention, an
international treaty governing dumping at sea, issued a “statement of
concern” about the work and a United Nations
group called for a moratorium, but it is not clear what would have
happened had Planktos not abandoned the effort for lack of money.

Here is the whole story.

Are lead papers in a journal of higher quality?

Maybe not, maybe you just think they are:

Leading papers in a journal’s issue attract, on average, more citations than those that follow.  It is, however, difficult to assess whether they are of better quality (as is often suggested), or whether this happens just because they appear first in an issue. We make use of a natural experiment that was carried out by a journal in which papers are randomly ordered in some issues, while this order is not random in others. We show that leading papers in randomly ordered issues also attract more citations, which casts some doubt on whether, in general, leading papers are of higher quality.

Here is the full paper, courtesy of Pluralist Economics Review.

The nature of ability bias

Remember all those studies showing that people claim they are above-average drivers?  Or above-average at other things they do?  It may not just be self-deception.  Here is the latest:

…we find it easier to consider the favourable evidence for a single
person than we do for a whole group. Consistent with this is the
finding that people tend to be biased when comparing any single
individual, not just themselves, against a group of others.

There’s
also the possibility that we’re biased towards the "target" in any
comparison. The "target" is the entity that is being measured up
against some benchmark. Following this logic, if I asked you how good
all other drivers are compared with you (thus making other drivers the
"target" of the comparison and you the benchmark), then this ought to
reduce the bias you’d show towards yourself.

…A new study has tried to get to the bottom of what causes the "above
average effect" by pitching these three explanations against each
other. Zlatan Krizan
and Jerry Suls Dozens asked dozens of undergraduates to list a group of
friends or acquaintances, to take one member of that group and then
compare that individual with the rest of the group on some attribute –
say, generosity.

Of the three factors, our difficulty in seeing the quality of a group, relative to the quality of an individual, seems to be the primary source of bias in the ranking. 

Fortunately, I am better at avoiding that bias than are my readers.

Hypergamy is the word of the day.

Yes, men are also, to their own detriment, continually surrounded with images of exceptionally attractive women. But this has less practical import, because–to say it once more–women choose.

Or:

The decline of matrimony is often attributed to men now being able to “get what they want” from women without marrying them. But what if a woman is able to get everything she wants from a man without marriage? Might she not also be less inclined to “commit” under such circumstances?

This essay is not politically correct and at times it is misogynous and yes I believe the author is evil (seriously).  The main behavioral assumption is that women are fickle.  So they are monogamous at points of time but not over time; Devlin then solves for the resulting equilibrium, so to speak.  The birth rate falls, for one thing.  The piece also claims that the modern "abolition" of marriage strengthens the attractive at the expense of the unattractive.  Some of you will hate the piece.  I disagree with the central conclusion, and also the motivation, but it does seem to count as a new idea.  If you’re tempted, read it.

I thank Robin Hanson for the pointer.

Summers Vindicated (again)

For the past week or so the newspapers have been trumpeting a new study showing no difference in average math ability between males and females.  Few people who have looked at the data thought that there were big differences in average ability but many media reports also said that the study showed no differences in high ability.

The LA Times, for example, wrote:

The study also undermined the assumption — infamously espoused by former Harvard University President Lawrence H. Summers in 2005 — that boys are more likely than girls to be math geniuses.

Scientific American said:

So the team checked out the most gifted children. Again, no difference. From any angle, girls measured up to boys. Still, there’s a lack of women in the highest levels of professional math, engineering and physics. Some have said that’s because of an innate difference in math ability. But the new research shows that that explanation just doesn’t add up.

The Chronicle of Higher Education said:

The research team also studied if there were gender discrepancies at the highest levels of mathematical ability and how well boys and girls resolved complex problems. Again they found no significant differences.

All of these reports and many more like them are false.  In fact, consistent with many earlier studies (JSTOR), what this study found was that the ratio of male to female variance in ability was positive and significant, in other words we can expect that there will be more math geniuses and more dullards, among males than among females.  I quote from the study (VR is variance ratio):

Greater male variance is indicated by VR > 1.0. All VRs, by state and grade, are >1.0 [range 1.11 to 1.21].

Notice that the greater male variance is observable in the earliest data, grade 2.  (In addition, higher male VRS have been noted for over a century).  Now the study authors clearly wanted to downplay this finding so they wrote things like “our analyses show greater male variability, although the discrepancy in variances is not large.”  Which is true in some sense but the point is that small differences in variance can make for big differences in outcome at the top.  The authors acknowledge this with the following:

If a particular specialty required mathematical skills at the 99th percentile, and the gender ratio is 2.0, we would expect 67% men in the occupation and 33% women. Yet today, for example, Ph.D. programs in engineering average only about 15% women.

So even by the authors’ calculations you would expect twice as many men as women in engineering PhD programs due to math-ability differences alone (compare with the media reports above).  But what the author’s don’t tell you is that the gender ratio will get larger the higher the percentile.  Larry Summers in his infamous talk, was explicit about this point:

…if one is talking about physicists at a top twenty-five research university, one is not talking about people who are two standard deviations above the mean…But it’s talking about people who are three and a half, four standard deviations above the mean in the one in 5,000, one in 10,000 class. Even small differences in the standard deviation will translate into very large differences in the available pool substantially out.

If you do the same type of calculation as the authors but now look at the expected gender ratio at 4 standard deviations from the mean you find a ratio of more than 3:1, i.e. just over 75 men for every 25 women should be expected at say a top-25 math or physics department on the basis of math ability alone (see the extension for details on my calculation).  Now does this explain everything that is going on?  I doubt it.  As Summers also pointed out it takes more than ability to become a professor at Harvard and if there are variance differences in characteristics other than ability (and there are) we can easily get a even larger expected gender ratio.

Does this mean that discrimination is not a problem?  Certainly not but we need the media and academia to accurately present the data on ability if we are to understand how large a role other issues may play.

Addendum 1: Andrew Gelman points out that perhaps alone among the media, Keith Winstein at the WSJ reported the story correctly.

Addendum 2: The authors show variance ratios of 1.11 to 1.21, I take a VR of 1.16.  If we set the female variance to 1 this implies the standard deviation for female ability is 1 and for male ability 1.077.  Using an online calculator for the Normal distribution you can find that given their standard deviation .0102% of males have ability of 4 or greater (4 female sds) but given their sd only .0032% of females can be expected to have the same level of ability, thus a gender ratio of 3.18.

Note that we are assuming that mathematical ability is normally distributed – we know the data fit this distribution around the mean but we don’t know much about what happens at the very top.

Group Theory in the Bedroom

I had never thought of this:

In a sense, base 3 is the best of the integer bases because 3 is the integer closest to e…Suppose you are creating one of those dreaded telephone menu systems — press 1 to be inconvenienced, press 2 to be condescended to, and so forth.  If there are many choices, what is the best way to organize them?  Should you build a deep hierarchy with lots of little menus that each offer just a few options?  Or is it better to flatten teh structure into a few long menus?  In this situation a reasonable goal is to minimize the number of options that the wretched caller must listen to before finally reaching his or her destination.  The problem is analogous to that of representing an integer in positional notation: the number of items per menu corresponds to the radix r, and the number of menus is analogous to the width w.  The average number of choices to be endured is minimized when there are three items per menu.

I have no idea if it is correct.  It is from the often quite interesting Group Theory in the Bedroom, and Other Mathematical Diversions, by Brian Hayes.

The Eureka Hunt

This stimulating New Yorker essay (right now gated, but worth buying the issue for) focuses on where creative moments come from.  Excerpt:

Many stimulants, like caffeine, Adderall, and Ritalin, are taken to increase focus — one recent poll found that nearly twenty percent of scientists and researchers regularly took prescription drugs to "enhance concentration" — but, accordingly to Jung-Beeman and Kounios, drugs may actually make insights less likely, by sharpening the spotlight of attention and discouraging mental rambles.  Concentration, it seems, comes with the hidden cost of diminished creativity.  "There’s a good reason Google puts Ping-Pong tables in their headquarters," Kounios said.  "If you want to encourage insights, then you’ve got to also encourage people to relax."  Jung-Beeman’s latest paper investigates why people who are in a good mood are so much better at solving insight puzzles.  (On average, they solve nearly twenty percent more C.R.A. problems.)

Who wants cryonics?

Arnold Kling reports:

[Robin] Hanson says that the expected return from being cryonically frozen is positive. If it works, the benefits are high, and the probability of it working is greater than zero. Yet few people sign up for it. I think that we are afraid of looking weird if we sign up for it.

I wonder if people who already look weird, for whatever reason, sign up at disproportionate rates.  I suspect not and that only some very particular preexisting unusual traits predict an interest in cryonics.  Is the best predictor of signing up is interest in science fiction?  If so, does this mean that the non-signers are simply people who are not able to imagine the potential benefits?  Or does an interest in science fiction already label the person in some way where the marginal image cost of signing up is then especially low?  Both cryonics and science fiction of course have very high rates of male participation, some exceptions aside.  I predict that the reading of fantasy novels does not so well correlate with interest in cryonics, once you adjust for any prior interest in science fiction.

A Girl Named Florida

I’ve been reading Leonard Mlodinow’s The Drunkard’s Walk: How Randomness Rules our Lives.  The book covers the Monty Hall problem, Bayes’s Theorem, availability bias, the illusion of control and so forth.  If these are unfamiliar, look no further for an entertaining account.

On the other hand, I can’t say that I learned much I didn’t already know.  Nevertheless, I still enjoyed reading the book – it’s well written and filled with interesting nuggets (Did you know that the great mathematician Paul Erdos refused to believe that you should switch doors?).  If you teach probability theory or intro stats you will find lots of good examples to brighten up your lectures. 

One problem did intrigue me.  Suppose that a family has two children.  What is the probability that both are girls?  Ok, easy.  Probability of a girl is one half, probabilities are independent thus probability of two girls is 1/2*1/2=1/4.

Now what is the probability of having two girls if at least one of the children is a girl?  A little bit harder.  Temptation is to say that if one is a girl the probability of the other being a girl is 1/2 so the answer is 1/2.  That’s wrong because you are not told which of the two children is a girl and that makes a difference.  Better approach is to note that without any additional information there are four possibilities of equal likelihood for the sex of two children (B,B), (G,B), (B,G), (G,G).  If we know that at least one is a girl we can remove (B,B) so three equally likely possibilities, (G,B), (B,G), (G,G), remain and of these 1 has two girls so the answer is 1/3.

Ok, now here is the stumper.  What is the probability of a family having two girls if one of the children is a girl named Florida?

At first it seems impossible that knowing the name should make a difference.  Surely, the answer is 1/3 just as before?  After all, every child has a name.  But knowing the name does make a difference.  Here’s a hint, Florida is a rare name.

Mental activity halts some of your self-deception and hypocrisy

The main idea is that when you busy people’s minds with a routine task, they are less able to rationalize their own behavior and they are more likely to report the truth about what they are doing.  The most quotable excerpt assumes a bit of context

To find out, he and Dr. Valdesolo brought more people into the lab
and watched them selfishly assign themselves the easy task. Then, at
the start of the subsequent questioning, some of these people were
asked to memorize a list of numbers and retain it in their heads as
they answered questions about the experiment and their actions.

That
little bit of extra mental exertion was enough to eliminate hypocrisy.
These people judged their own actions [in assigning themselves the easy task] just as harshly as others did.
Their brains were apparently too busy to rationalize their selfishness,
so they fell back on their intuitive feelings about fairness.

If you wish, here is the whole piece.

What determines fertility?

Here are some thoughts:

So there would seem to be two models for achieving higher fertility:
the neosocialist Scandinavian system and the laissez-faire American
one. Aassve put it to me this way: “You might say that in order to
promote fertility, your society needs to be generous or flexible. The
U.S. isn’t very generous, but it is flexible. Italy is not generous in
terms of social services and it’s not flexible. There is also a social
stigma in countries like Italy, where it is seen as less socially
accepted for women with children to work. In the U.S., that is very
accepted.”

By this logic, the worst sort of system is one that
partly buys into the modern world – expanding educational and
employment opportunities for women – but keeps its traditional
mind-set. This would seem to define the demographic crisis that Italy,
Spain and Greece find themselves in – and, perhaps, Japan, South Korea,
Hong Kong, Taiwan and other parts of the world. Indeed, demographers
have been surprised to find rapid fertility changes in the third world,
as more and more women work and modern birth-control methods become
standard options. “The earlier distinct fertility regimes, ‘developed’
and ‘developing,’ are increasingly disappearing in global comparisons
of fertility levels,” according to Edward Jow-Ching Tu…the birthrate in 25 developing countries – including Cuba, Costa Rica,
Iran, Sri Lanka and China – now stands at or below the replacement
level.

Loanwords

Eating lunch in a working man’s restaurant in Hong Kong I hear mostly Cantonese but with occassional English words, "passion," for example.  Borrowed words or loanwords surely tell us something important about ideas or concepts that the first language lacks.  Most loanwords are for things (e.g. mouse for a computer device), it’s pretty easy to explain the adoption of such words.  But what about words for which the thing has always existed but not the word?  Chinese speakers tell me that there is a word for love but passion is more difficult to translate.

What are some of the major conceptual loanwords?  What do loanwords tell us about the Sapir-Whorf hypothesis? What loanwords does English need?  There appears to be a large literature in linguistics on the adoption and evolution of loanwords but less on the cultural significance of loanwords.  Comments?