Category: Data Source

The Divorce Myth

by  Justin Wolfers in

I want to start my week guest blogging by talking about divorce. Betsey Stevenson and
I had an
op-ed in yesterday’s New York Times noting a very simple fact: those
married in the 1990s have proved less likely to divorce than those wed in the
1980s, which were less likely to divorce than those wed in the 1970s. The
Divorce Facts are that divorce is falling, and marriages are more stable.

What is surprising, is just how easily and how often the
Divorce Facts lose out to the Divorce Myth. The Divorce Myth is that divorce
is rising. When the latest
divorce numbers came out last week, they once again confirm this
quarter-century long decline in divorce, but the media (including the Times,
Post,
and the Inquirer)
chose instead to write (incorrectly) about rising divorce. (In their defense, the data were presented in
a way that invited misinterpretation, a subject that I shall return to in a
future post.)

Why the persistence of the Divorce Myth?

  1. Blame the
    public for underestimating divorce    : Tyler
    has argued     that Americans “underestimate the probability of divorce”, and
    so when the statistics show that divorce is quite common, they infer divorce
    must have risen.
  2. Blame the
    public for overestimating divorce    : Greg
    Mankiw thinks     that this “seems be an example of what Bryan Caplan calls ‘the
    pessimistic bias’, a tendency to overestimate the severity of economic problems.”
  3. Blame the
    press    : Mankiw may be a bit unfair on Joe Citizen: the average person gets
    their news from the press, and in this case, the press reported falsehoods as
    facts.
  4. Blame the
    politics    : We argued that “Reporting on our families is a lot like reporting
    on the economy: statistical tales of woe provide the foundation for reform
    proposals. The only difference is that
    conservatives use these data to make the case for greater government
    intervention in the marriage market, while liberals use them to promote
    deregulation of marriage.”
  5. Blame the
    professors    : Academics are meant to provide the facts offsetting the
    political hacks. But we don’t. Economists have had too little respect for
    simple facts; publication glory lies with grand theories. Ideologically-motivated profs teaching family
    sociology or family law would rather reinforce the Myth than offset it.

Personally, I go for #4 causing #3, unchecked by #5, and
would love to see research by Bryan testing #1 v. #2.  Your thoughts?

Heroes are not Replicable

by  Alex Tabarrok in

You know the plot.  Young, idealistic teacher goes to inner-city high school.  Said idealistic teacher is shocked by students who don’t know the basics and who are too preoccupied with the burdens of violence, poverty and indifference to want to learn.  But the hero perseveres and at great personal sacrifice wins over the students using innovative teaching methods and heart.  The kids go on to win the state spelling/chess/mathematics championship.  c.f. Stand and Deliver, Freedom Writers, Dangerous Minds etc.

We are supposed to be uplifted by these stories but they depress me.  If it takes a hero to save an inner city school then there is no hope.  Heroes are not replicable.

What we need to save inner-city schools, and poor schools everywhere, is a method that works when the teachers aren’t heroes.  Even better if the method works when teachers are ordinary people, poorly paid and ill-motivated – i.e. the system we have today. 

In Super Crunchers, Ian Ayres argues that just such a method exists.  Overall, Super Crunchers is a light but entertaining account of how large amounts of data and cheap computing power are improving forecasting and decision making in social science, government and business.  I enjoyed the book.  Chapter 7, however, was a real highlight.

Ayres argues that large experimental studies have shown that the teaching method which works best is Direct Instruction (here and here are two non-academic discussions which summarizes much of the same academic evidence discussed in Ayres).  In Direct Instruction the teacher follows a script, a carefully designed and evaluated script.  As Ayres notes this is key:

DI is scalable.  Its success isn’t contingent on the personality of some uber-teacher….You don’t need to be a genius to be an effective DI teacher.  DI can be implemented in dozens upon dozens of classrooms with just ordinary teachers.  You just need to be able to follow the script.

Contrary to what you might think, the data also show that DI does not impede creativity or self-esteem.  The education establishment, however, hates DI because it is a threat to the power and prestige of teaching, they prefer the model of teacher as hero.  As Ayres says "The education establishment is wedded to its pet theories regardless of what the evidence says."  As a result they have fought it tooth and nail so that "Direct Instruction, the oldest and most validated program, has captured only a little more than 1 percent of the grade-school market." 

Sentences of provocation

by  Tyler Cowen in

Our results suggest that if all states had primary enforcement seatbelt laws then regular youth seatbelt use would be nearly universal and youth fatalities would fall by about 120 per year.

Here is the paper.  My question: how many expected saved lives are required for this law to be a good idea?  Any comment on this post should suggest a specific numerical answer to that question.

Facts about rich people

by  Tyler Cowen in

In the first Forbes 400 [1982], oil was the source of 22.8 percent of the fortunes, manufacturing 15.3 percent, finance 9 percent, and technology 3 percent.  By 2006 oil had fallen to 8.5 percent and manufacturing to 8.5 percent.  Technology, however, had risen to 11.75 percent and finance to an extraordinary 24.5 percent.

And get this:

The average net worth in 2006 of Forbes 400 members without a college degree was $5.96 billion; those with a degree averaged $3.14 billion.  Four of the five richest Americans — Bill Gates, casino owner Sheldon Adelson, Oracle’s Larry Ellison, and Microsoft cofounder Paul Allen…– are college dropouts.

Both are from the quite engaging All the Money in the World — How the Forbes 400 Make — And Spend — Their Fortunes, by Peter W. Bernstein and Annalyn Swan.

In inflation-adjusted terms, here are the richest Americans of all time; Bill Gates is #13.  Here are graphs on California vs. New York.

Suicide help lines

by  Tyler Cowen in

In 723 of 1,431 calls, for example, the helper never got around to asking whether the caller was feeling suicidal.  And
when suicidal thoughts were identified, the helpers asked about
available means less than half the time.  There were more egregious
lapses, too: in 72 cases a caller was actually put on hold until he or
she hung up.  Seventy-six times the helper screamed at, or was rude to,
the caller.  Four were told they might as well kill themselves.

There were 33 evident on-line suicide attempts, yet only six rescue
efforts, sometimes because the caller ended the communication.  In one
case, a caller who’d overdosed passed out, yet the helper hung up.

Here is the full story, by Christopher Shea.  I am curious how much of this problem is due to the non-profit structure of the institutions running the lines and how much is due to the behavioral quirks of human beings faced with the suicidal tendencies of others…

From the comments: "Also, how would a for-profit suicide hotline work? Call a 900 number if
you’re having suicidal thoughts? I find it hard to imagine that a
for-profit suicide hotline system would generate *more* suicide
prevention, though maybe I’m wrong."

Prediction tools

by  Tyler Cowen in

Predict How Long You’ll Live (Northwest Mutual)

Predict Your Child’s Due Date (Ayres)

Predict Your Child’s Adult Height (University of
Saskatchewan)

Predict Justice Kennedy’s Vote (Ayres)

Predict Your Next Move in Rock-Paper-Scissors (Chappie)

There are many other prediction tools here (do click), from Ian Ayres.  Ayres requests that you email him other prediction applets, which he will add to the page.  Ayres also has a new book out, Super Crunchers: Why Thinking by Numbers is the New Way to be Smart; it is highly readable and also endorsed by Steve Levitt.

I thank Ian Ayres for the pointer.

Mobility

by  Tyler Cowen in

Here is the latest, by Emmanuel Saez and co-authors; note I linked to this paper yesterday but now I have looked at it.  Here is one key sentence:

…we find that short-term and long-term mobility among all workers has been quite stable since the 1950s.

To disaggregate, note that mobility among males is down but mobility among females is up.  (It is an interesting question whether there is a causal relationship here.)

Here is a much earlier MR post on mobility.  Keep these links in mind next time you hear claims about mobility, and I believe you will hear many such claims in September.  See also our earlier posts on Dalton Conley, who shows just how much inequality is generated within the same family.

It should be noted that Saez is the leading measurer of income inequality and also a critic of such inequality.  In his view a constant level of mobility means that no force is offsetting ongoing inequality.  I believe he would likely read his own paper as support for a left-wing view of the world and as support for concern with income inequality.  He would not read his work as reason to dismiss the mobility issue.  My view differs, as I worry about mobility — can a hard-working person get ahead? — but I do not worry about inequality per se, nor do I require of mobility that it overturn a particular level of inequality. 

Department of Yikes

by  Tyler Cowen in

Overall, 74 percent [of men visiting streetwalkers] reported that they always wear a condom (men with stable relationships were less likely to use protection, at least with prostitutes).

It’s not so hard to write down the underlying utility function here, is it?

That is from the September 2007 issue of Atlantic Monthly, citing research by economist Marina della Giusta and others, published in Applied Economics.  The working paper seems to be here.

In another development at Atlantic Monthly, but unrelated to the above factoid, or to the more general idea of yikes, the new Megan McArdle blog is now up and running.  Here is Megan’s post on what old people deserve.

Sunday cat blogging

by  Tyler Cowen in

Where do most tigers live?

In the United States it turns out.  There are 4,000 tigers residing in captivity in Texas alone, where private ownership of tigers is legal.  The number of tigers left in the wild is perhaps no more than 5,100-7,500.

A tiger cub costs about $1,000 while the more exotic blue-eyed white tiger costs $15,000.

That is from The Book of General Ignorance, an interesting compilation of not so well known facts. 

I learned also that chamelons do not change color to fit their background (the changes are determined by their emotional states), moths are disoriented by flames rather than attracted to them, and (possibly) America was named after Richard Amerike rather than Amerigo Vespucci; I still haven’t gotten to the bottom of that one.  Amerike, a wealthy merchant, helped finance Cabot’s voyage, and asked that any discovered lands be named after him.

Japan fact of the day

by  Tyler Cowen in

Analysts estimate that 20 percent of all luxury goods are sold in Japan and another 30 percent to Japanese traveling abroad — meaning Japanese buy half of all luxury goods.  Today, approximately 40 percent of all Japanese own a Vuitton product.

That is from Dana Thomas’s really quite interesting Deluxe: How Luxury Lost its Luster.  Thomas believes that the Japanese are so infatuated with luxury goods because they wish to brand themselves in what otherwise pretends to be a "classless" society.

Neglected growth miracles

by  Tyler Cowen in

Between 1962 and 2002, life expectancy in the Middle East and North Africa…increased from around 48 years to 69 years…it was…the strongest performance of any region in the world…

…China, which saw life expectancy growing at 1.6 percent in the 1960s, collapsing to around 0.2 percent in the 1980s and 1990s, while income growth was going in the other direction.

Did you know that The Gambia, Yemen, Bangladesh, Nepal, and Libya were all in the top ten gainers in life expectancy, 1962-2002?

Here is the paper.  Here is the guy’s (very interesting) blog, via Bryan Caplan.