Comments, observations and thoughts from two bloggers on applied statistics, higher education and epidemiology. Joseph is an associate professor. Mark is a professional statistician and former math teacher.
Sunday, July 18, 2010
This is exactly right
New blog alert
Definitely a site we'll want to keep an eye on.
Friday, July 16, 2010
The yahoos at Yahoo
I realize that Yahoo's homepage is not exactly a publication, but it does have tremendous reach and it would be nice if they hired someone to actually read what they post.
Thursday, July 15, 2010
Divergent and Convergent Learning
[There is an obvious connection between this divergent learning and the creativity discussion here, here, here and here]
There is an common but fatally naive misconception that convergent learning goes with math and science while divergent learning goes with arts and humanities. Almost all subjects start with a large convergent learning component including the arts (try picking up an instrument and see how much divergence your teacher tolerates in the first few lessons). More importantly, ALL subjects are fundamentally divergent at a high enough level. Writing a novel, composing a symphony, proving a conjecture or designing an aircraft are all creative exercises in constrained problem solving. We demand that certain conditions be met but we expect that each solution (or at least the method behind it) will be unique.
Which begs the disturbing question: will the proposed educational reforms produce more or fewer of the divergent thinkers we actually need?
p.s. Liam Hudson came up with a uses of objects test to measure divergent thinking. It ignores the complex interaction between possibility and constraint and is therefore, in my ever-humble opinion, complete crap, but take a look anyway.
Bias versus precision
But not all models are confounding models and the instincts that serve us so well for confounding models can be misleading for predictive models. Nate Silver has a very well explained example of how inaccurate (or, to be more formal, imprecise) predictive models can be worse than biased models. It's a very interesting confusion between bias and precision but it makes me wonder if we don't focus too much on unbiased and too little on efficiency for some of our models.
Thoughts?
Wednesday, July 14, 2010
More on creativity and slippery metrics
On of the classic criticism of scientific management is that they took a good idea (try and find measureable metrics of business success and failure) and turned it into a myopic focus on what is easy to measure in a spreadsheet. As a result, they focused on easy to measure metrics of success and, in the process, tended to neglect things that are hard to measure.
It's obviously true that creativity is a slippery and hard to measure concept. It is hard to, for example, design a standardized test around it. I wonder if part of the issues of education reform come from a focus on what can be measured and not what is important?
The best way to get rich is to sell books to gullible people
The best type of debt is debt that builds wealth over the long run, and the
No. 1 example of that is mortgage debt."Home values have increased an average of 6.5 percent a year over the past 30 years," says Bach. "So when you borrow to buy a home, chances are that's good debt. You'll build value."
Bach heavily promotes the idea of homeownership, saying that everyone needs to own where they live. "About 40 percent of Americans are renters," says Bach, "and the fastest way to wealth in America is buying where you live."
Bach cites some shocking numbers to back this up. "The average renter has a median net worth of $4,000, and the average homeowner has a median net worth of about $150,000."
...
One of the reasons so many Americans seem mired in bad debt (Bach reports that the average American carries approximately $8,400 in credit card debt) is that financial education is pratically (sic) nonexistent. "This type of commonsense stuff isn't taught in school," says Bach, "and most Americans don't realize how bad high-rate credit cards are hurting them."
Bach has been doling out this same advice complete with the same net worth statistic (apparently included under the assumption that schools didn't teach statistics either) for about a decade*. It is slightly more sound now than it was five years ago, but it is still not what you'd call good.
This ground has been covered before (notably by Felix Salmon) but just to recap:
1. Home ownership is not a particularly good investment either in terms of returns. It's bad in terms of liquidity and horrible in terms of diversification;
2. Analyses purporting to show the amount saved by owning vs. renting almost always overlook the direct and indirect costs associated with suburban commuting.
3. Home ownership makes it difficult for workers to go where the jobs are. This has economic consequences on the national level, but it's on the individual level that this can turn into a real horror show. Housing prices, liquidity and employment are all correlated by region.
*In Start Late, Finish Rich, Bach says "you cannot get rich being a renter."
Tuesday, July 13, 2010
Creativity
You can see this as technology progresses. Consider live music and plays over time. In 1890, if you wanted to hear music or see a story acted out in your home town then you needed to get a local musician to play or go to a local community theater. In 2010 you downloaded the music to your iPod or a top film to your television set.
You see this phenomenon with lots of things. When my dad did weight lifting in the 1960's, the best you could do was a book on the topic. People competed to invent new techniques (and likely had a lot of injuries as a result). Today, I can find massive amounts of information on the topic sitting at home. In the 1970's, Gary Gygax and company could create a new type of game (role-playing games) as an extension of war gaming. Today the ability to create a new game is much harder given the development costs.
So is the lack of creativity a symptom of a richer environment where finding rhea optimal solution is better than creating a new (and likely sub-optimal one)?
I am not saying that this is the case and Felix Salmon brings up a lot of other good points. But it's another reason to wonder about what the implications of these claims would be, even if they were to prove to be correct.
Monday, July 12, 2010
Net impact
Examples of these sorts of things include regulations, old laws (regarding horse thievery, for example) assistant professor committee work, software patches and so forth. For example, the last university I was at required a one hour course on the hazards of asbestos every year. While I am sure that asbestos is deadly substance, it seems like overkill to have a class on such a narrow topic every year.
What is hard to determine is how to identify these situations ahead of time and determine the appropriate responses. It's not easy -- as a junior professor I have said no to a few requests already that were pretty reasonable (and sounded like they'd add value) just to make sure that I had enough time.
I would like to think of a way to handle this issue that did not involve "over-all impact committees".
Saturday, July 10, 2010
Another reason not to aggregate elementary and post-elementary school data
In mathematics, fourth-grade students in 7 countries outperform our fourth graders (Singapore, Korea, Japan, Hong Kong, the Netherlands, the Czech Republic, and Austria). Students in 6 countries are not significantly different from ours (Slovenia, Ireland, Hungary, Australia, Canada, and Israel). U.S. fourth graders outperform their counterparts in 12 nations (Latvia, Scotland, England, Cyprus, Norway, New Zealand, Greece, Thailand, Portugal, Iceland, Islamic Republic of Iran, and Kuwait).In science, students in only one country--Korea--outperform U.S. fourth graders. Students in 5 countries are not significantly different than ours (Japan, Austria, Australia, the Netherlands, and the Czech Republic), and U.S. fourth graders outperform their counterparts in 19 nations (England, Canada, Singapore, Slovenia, Ireland, Scotland, Hong Kong, Hungary, New Zealand, Norway, Latvia, Israel, Iceland, Greece, Portugal, Cyprus, Thailand, Islamic Republic of Iran, and Kuwait).
*I'll try to dig up some more recent results just to see how things are trending.
Friday, July 9, 2010
If all students were 15 years old...
After bad metrics, I think the worst problem in educational research may be the inappropriate aggregation of primary and secondary education. If there was ever a case where two populations should be treated separately it's here. The two systems face different problems of different severity that respond to different solutions.
I'll try to follow up with some specifics later, but in the meantime, when you hear someone making a blanket proclamation about our schools, remember that about the only meaningful statement you can make that's true about primary and secondary schools is that the teachers in both are about to get screwed.
Statistical programming languages
These days I see the following languages in heavy use: STATA, R, SPSS, SAS and some S-plus. Furthermore, one is requires to do data management in some combination of SQL/Oracle, SAS, Excel and Access. That doesn't even touch on the people who still use C++ and/or FORTRAN for specialized programming applications.
My question is which ones does it make sense to support? In my department, I think we'll do a combination of R (freeware, flexible, powerful) and SAS (FDA standard) as languages that we officially support. But not supporting STATA is a very painful choice! What have others done in similar circumstances?
Speaking for the unhinged
Jonathan Chait dismisses critics of proposed education reform as 'unhinged.' Speaking as one of the whackjobs, here's the sort of thing that makes us loonies so nervous.
From a press release (6/8/09) from the Department of Education:
Emphasizing the need for additional effective education entrepreneurs to join the work of reforming America's lowest performing public schools, U.S. Secretary of Education Arne Duncan told reporters during a conference call this afternoon that states must be open to charter schools. Too much is at stake for states financially and for students academically to restrict choice and innovation.
"States that do not have public charter laws or put artificial caps on the growth of charter schools will jeopardize their applications under the Race to the Top Fund," Secretary Duncan said. "To be clear, this administration is not looking to open unregulated and unaccountable schools. We want real autonomy for charters combined with a rigorous authorization process and high performance standards."
From a May 1st story in the New York Times:
But for all their support and cultural cachet, the majority of the 5,000 or so charter schools nationwide appear to be no better, and in many cases worse, than local public schools when measured by achievement on standardized tests, according to experts citing years of research. Last year one of the most comprehensive studies, by researchers from Stanford University, found that fewer than one-fifth of charter schools nationally offered a better education than comparable local schools, almost half offered an equivalent education and more than a third, 37 percent, were “significantly worse.”Us nutjobs would like to see the administration reconsider its position based on the data.
Thursday, July 8, 2010
"Fewer Low-Income Students Going to College"
Fewer low- and moderate-income high school graduates are attending college in America, and fewer are graduating.
Enrollment in four-year colleges was 40% in 2004 for low-income students, down from 54% in 1992, and 53% in 2004 for moderate-income students, down from 59% over the same period, according to a report recently submitted to Congress by the Advisory Committee on Student Financial Assistance.If that trend has continued, low- and moderate-income students who don’t move on to college face an even darker outlook. The unemployment rate for 16- to 19-year olds averaged 17% in 2004, the jobless rate for people over age 25 with just a high school diploma averaged 5% the same year. So far this year, those figures have jumped to 25.8% and 10.6%, respectively.
College expenses and financial aid have become increasingly larger considerations for parents and students, driving more qualified students away from enrolling in four-year colleges.
Wednesday, July 7, 2010
Harm Reduction
The findings were dramatic:
For each additional year of opiate substitution treatment the hazard of death before long term cessation fell 13% (95% confidence interval 17% to 9%) after adjustment for HIV, sex, calendar period, age at first injection, and history of prison and overdose.
This is a massive effect. Just one year of treatment is competitive with interventions that we would not even think twice about: many drug treatments for cardiovascular disease fall into this range. Since we can't really randomize people to these types of treatments, the prospective cohort design is likely as good as it gets. So perhaps these types of dramatic findings, if properly replicated, can start a discussion about harm reduction once the behavior is initiated. After all, there is a large population of injectable drug users and finding ways to improve their (fairly poor) outcomes seems like a decent way to improve public health.