Fiscal prudence (a never ending saga)

This is an important point about financial planning from Megan McArdle:

When people end up in financial trouble, you often hear tsk-tsking about premium cable and fancy vacations. But if you talk to bankruptcy lawyers and financial counselors, that isn't the normal story you hear. You're more likely to hear about car loans, mortgages, alimony. In other words, it's not the luxury splurges that do you in -- it's the fixed expenses. That's because discretionary luxury expenses can be cut in an emergency, while the fixed payments go on and on until they empty your bank account.

She might be a libertarian in her politics, but she is a lot like a Canadian in terms of fiscal prudence.  Now I agree that there may be larger social issues that are making it harder for people to meet fixed expenses (e.g. wage stagnation) but at an individual level this is a calculation well worth making. 

On SAT changes, The New York Times gets the effect right but the direction wrong

That was quick.

Almost immediately after posting this piece on the elimination of the SAT's correction for guessing (The SAT and the penalty for NOT guessing), I came across this from Todd Balf in the New York Times Magazine.

Students were docked one-quarter point for every multiple-choice question they got wrong, requiring a time-consuming risk analysis to determine which questions to answer and which to leave blank. 

I went through this in some detail in the previous post but for a second opinion (and a more concise one), here's Wikipedia:

The questions are weighted equally. For each correct answer, one raw point is added. For each incorrect answer one-fourth of a point is deducted. No points are deducted for incorrect math grid-in questions. This ensures that a student's mathematically expected gain from guessing is zero. The final score is derived from the raw score; the precise conversion chart varies between test administrations.

The SAT therefore recommends only making educated guesses, that is, when the test taker can eliminate at least one answer he or she thinks is wrong. Without eliminating any answers one's probability of answering correctly is 20%. Eliminating one wrong answer increases this probability to 25% (and the expected gain to 1/16 of a point); two, a 33.3% probability (1/6 of a point); and three, a 50% probability (3/8 of a point). 

You could go even further. You don't actually have to eliminate a wrong answer to make guessing a good strategy. If you have any information about the relative likelihood of the options, guessing will have positive expected value.

The result is that, while time management for a test like the SAT can be complicated, the rule for guessing is embarrassingly simple: give your best guess for questions you read; don't waste time guessing on questions that you didn't have time to read.

The risk analysis actually becomes much more complicated when you take away the penalty for guessing. On the ACT (or the new SAT), there is a positive expected value associated with blind guessing and that value is large enough to cause trouble. Under severe time constraints (a fairly common occurrence with these tests), the minute it would take you to attempt a problem, even if you get it right, would be better spent filling in bubbles for questions you haven't read.

Putting aside what this does to the validity of the test, trying to decide when to start guessing is a real and needless distraction for test takers. In other words, just to put far too fine a point on it, the claim about the effects of the correction for guessing aren't just wrong; they are the opposite of right. The old system didn't  require time-consuming risk analysis but the new one does.

As I said in the previous post, this represents a fairly small aspect of the changes in the SAT (loss of orthogonality being a much bigger concern). Furthermore, the SAT represents a fairly small and perhaps even relatively benign part of the story of David Coleman's education reform initiatives. Nonetheless, this one shouldn't be that difficult to get right, particularly for a publication with the reputation of the New York Times.

Of course, given that this is the second recent high-profile piece from the paper to take an anti-SAT slant, it's possible certain claims weren't vetted as well as others.

The SAT and the penalty for NOT guessing

Last week we had a post on why David Coleman's announcement that the SAT would now feature more "real world" problems was bad news, probably leading to worse questions and almost certainly hurting the test's orthogonality with respect to GPA and other transcript-based variables. Now let's take a at the elimination of the so-called penalty for guessing.

The SAT never had a penalty for guessing, not in the sense that guessing lowed your expected score. What the SAT did have was a correction for guessing. On a multiple-choice test without the correction (which is to say, pretty much all tests except the SAT), blindly guessing on the questions you didn't get a chance to look at will tend to raise your score. Let's say, for example, two students took a five-option test where they knew the answers to the first fifty questions and had no clue what the second fifty were asking (assume they were in Sanskrit). If Student 1 left the Sanskrit questions blank, he or she would get fifty point on the test. If Student 2 answered 'B' to all the Sanskrit questions, he or she would probably get around sixty points.

From an analytic standpoint, that's a big concern. We want to rank the students based on their knowledge of the material but here we have two students with the same mastery of the material but with a ten-point difference in scores. Worse yet, let's say we have a third student who knows a bit of Sanskrit and manages to answer five of those questions, leaving the rest blank thus making fifty-five points. Student 3 knows the material better than Student 2 but Student 2 makes a higher score. That's pretty much the worst possible case scenario for a test.

Now let's say that we subtracted a fraction of a point for each wrong answer -- 1/4 in this case, 1/(number of options - 1) in general -- but not for a blank. Now Student 1 and Student 2 both have fifty points while Student 3 still has fifty-five. The lark's on the wing, the snail's on the thorn, the statistician has rank/ordered the population and all's right with the world.

[Note that these scales are set to balance out for blind guessing. Students making informed guesses ("I know it can't be 'E'") will still come out ahead of those leaving a question blank. This too is as it should be.]

You can't really say that Student 2 has been penalized for guessing since the outcome for guessing is, on average, the same as the outcome for not guessing. It would be more accurate to say that 1 and 3 were originally penalized for NOT guessing.

Compared to some of the other issues we've discussed regarding the SAT, this one is fairly small, but it does illustrate a couple of important points about the test. First, the SAT is a carefully designed tests and second, some of the recent changes aren't nearly so well thought out.

Why I am optimistic about 538

As people may or may not know, Nate Silver has launched an independent website.  Some of the people whom I respect the most on the internet (Noah Smith, Paul Krugman, Andrew Gelman) have pointed out some of the teething problems, where the inclusion of either more data or more model information in the article would have been helpful. 

In essence, I think that the website is trying to balance a number of things at the same time:

1. Use of predictive statistical models
2. Accessible journalism
3. Thought provoking/contrarian views
4. A diverse body of topics

All of these elements can be important, but there can be a steep learning curve as to where the value is to the news consumer.  For example, Andrew Gelman points out in the sports column (as I best understand it -- I know nothing about sports and I am going entirely on the model comments) that he is having trouble figuring out the underlying model which makes interpretation more complicated.   In the comments, there was a request for the correlation matrix, which is deadly reasonable in the statistics field but might not appeal to the median reader.

So why am I optimistic?  Because Nate Silver has tended to be very data driven in his endeavours.  I have a strong prior expectation that the initial offerings are, at least partially, a test to see where he can add value relative to other media services (both on and off of the web).  Under these conditions, a good empirical tester would deliberating try out approaches and opinions that will likely fail.  Because that is the only way to get actual data on what works and to find unexploited niches. 

If people constantly want more statistics and articles with well described models (or links to well described models) do well then I bet we will see a lot more of them.  Or at least I hope so. 

So I am going to wait for about 90 days and then see what the site looks like.  I could be wrong about this approach -- but I am willing to put my opinion out there and see if the data support it going forward. 

A tentative foray into e-publishing

Regulars may have noticed that the blog went a bit fallow in late April and early March, though Joseph (who is disgustingly hardworking) picked up a great deal of the slack. My time was being diverted into putting together a couple of small books of puzzles from the Thirties and Forties and, sometimes more dauntingly, learning the subtleties of Kindle publishing.

The titles are "Classic Puzzles for the Classroom" and "Classic Word Puzzles for the Classroom." Other than some pagination and layout issues (more on that later in the post), the results were fairly close to what I had in mind. I believe they meet Abraham Lincoln's famous standard of literary acceptability: people who like this sort of thing will find in this the sort of thing they like.

Both books are collections of puzzles and games from Golden Age comics, selected from books now in the public domain and arranged in teacher-friendly sections. The target audience is small but the material was a good fit with the ongoing math ed and mathematical recreation threads here and at You Do the Math (which is about to go active again). I'll come back to the actual puzzles in future posts. For now though, here are a few notes on my (very limited) experience with e-books.

I like old comic books to look like old comic books, but not too much. Since I was using publicly available scans of very old magazines, some retouching was necessary but I tried to make it as unobtrusive as possible. I used GIMP for individual touch-ups and ImageMagick for things like rescaling large numbers of pictures. I'm no expert on graphics (more of a video guy) but the learning curve wasn't bad at all.

I had initially planned on doing the books as PDFs but Amazon's instructions said that would cause formatting problems and suggested submitting Word documents instead so that's what I did. I'm not sure it helped. Based on my experience and what I've read since, Kindle e-books are not a graphics-friendly format and, unfortunately, I was doing a couple of picture book. Formatting and pagination changed from device to device and, in the case of the Kindle preview function, changed while viewing the document on the same device -- as I flipped back and forth through the preview, a picture that started out on page nine might be on page ten when I flipped back. I tried playing with formatting and inserting a break for every new page but I eventually accepted defeat and simply left the page numbers out of the index with an explanatory note.

Recently, I came across a tool called Kindle Comic Creator, which I will try if I do another graphics-heavy e-book.

The rest of the publishing process was remarkably easy. The online form is fairly short and if I hadn't had to keep uploading reformatted drafts the process would probably have taken an hour or two.

I'll open the floor for suggestions now. Does anyone out there have relevant e-publishing experience to share?

This is also true in Epidemiology

Frances Woolley is back with a great post on how junior people focus on the statistical models and not the data set itself.  This is unfortunate as domain-specific knowledge of the data and the expected relations in the data is often the most important contributions.  When I worry about "field-jumping", it is this sort of problem that jumps up:

But all else is not equal. Using probit will not save a regression that combines men and women together into one sample when estimating the impact of having young children on the probability of being employed, and fails to include a gender*children interaction term. (The problem here is that children are associated with a higher probability of being employed for men, and a lower probability of being employed for women. These two effects cancel out in a sample that includes both men and women.)

Here we have a well understood and theoretically clear interaction that could easily be missed if one was not aware the body of work under-pinning it. 

It's also why I am suspicious of simplistic explanations for why entire fields have missed the obvious confounder/true exposure.  It is possible that this is true, but a command of the literature is needed to really understand why such a blind spot developed.  Which is not to say outsiders never bring in value (the Emperor has no clothes effect really exists).  But that I am much happier when I see a very detailed command of the data being used, the questions that were asked, the population that was included, ways in which the data collection may have influenced the results, and so forth.

Definitely go and read.

SAT winners and losers

One thing I've noticed about the recent calls to end the SAT is that the test is framed entirely as an obstacle. At no point is there any suggestion that some students might have more educational opportunity because of the test. Obviously that can't be true. There is clearly a zero sum aspect to this. When someone bombs their SAT, Harvard does not reduce its admissions by one.

This pool of those likely to gain is quite large. Having gone to a perfectly good but not outstanding public high school in the middle of the country, I can tell you that the best and often the only feasible way for most students to catch the eye of an elite college recruiter (with the possible exception of athletic accomplishment) is through high SAT scores. It is possible for a valedictorian from a no-name high school to get in to an Ivy League school without killer test scores, but they won't be pursued the way students who have broken 700 across the board on the SAT will. For a a lot of middle-class students, the SAT and ACT represent their best chances at a really prestigious school, not to mention the scholarships most Americans need to attend those schools.

This suggest an interesting framework for looking at the likely winners and losers under the current SAT system. Let's define winners as those for whom the potential benefits of a very high score are larger than the potential downside from an average or below score and losers as the opposite.

What would these two groups tend to look like? We have already partially answered this question for the winners. They would come from no name public high schools. They would tend not live near a major academic center such as the Northeast or Central or Southern California (since proximity increases the chance of networking). They would be middle or lower income (or at least low enough for twenty or thirty thousand of annual tuition to be a significant hardship).

How about the losers by the standard? Remember these are people who would gain relatively little from a very high score. That rules out anyone not fairly well to do (most of the rest of us can really use a full ride scholarship). They would probably attend the kind of elite and very pricey prep schools that are expert at getting their students into top universities. They would have the support network of connections and role models that make the application process go much smoother.

We previously discussed the op-ed by Jennifer Finney Boylan. Boylan clearly saw herself as someone who was more likely to be hurt than helped by the SAT so it would be interesting to see how well her background matches the group above. A quick stop at Wikipedia reveals that, though Boylan has overcome many challenges in her life, academic hardship does not appear to have been one of them. At the time her anecdote took place, she was about to graduate from the Haverford School. Haverford is almost a living cliche of an elite prep school, one of those places where the rich and powerful graduate from and send their children to.

It's true that there are ways that people with money can gain an advantage on the SAT. There are, however, considerably more and more effective ways that people with money and position can gain an advantage in all of the other factors used to rank potential college applicants: grades; school standing; extracurricular activities; recommendations; connections; the daunting application process. Students in Boylan's position have massive advantages. You could make the case that, as a high school student competing for a spot in an prestigious university, the only time Boylan had to compete on a roughly even playing field was when she took the SAT and it is worth noting that she resents it to this day.

That said, I don't want to single Boylan out. My concern here is with the insularity of the elites in our society and with the way that certain media outlets, particularly the New York Times, have come to view the world from their vantage point.

Weekend blogging -- What kind of urban culture attracts the creative class? (answered in comic strip form)

About a month ago, we had an interesting discussion here and on Andrew Gelman's blog regarding Richard Florida's theories about the creative class and urban culture (see here, here and here). It got me thinking about one of Florida's favorite examples, Austin, Texas. These days when people think of the culture of that town, the first name that generally comes to mind is South by Southwest, but it's important to note that SxSW came after Dell.

If you were to have asked people in 1980 (shortly before the town started becoming a tech center) about Austin's culture, I suspect the answers would have focused on two main topics: the first would be the outlaw country scene (contrary to the song, Waylon and Willie actually hung out in Austin. Nobody hung out in Luckenbach); the second would be the then dominant effect of the massive UT campus on the town.

You can get a pretty good idea what people thought of that UT/frat dominated culture, from the Academia Waltz, Berkeley Breathed's first cartoon and something of a proto-Bloom County.

Question of the day

Roger Farmer:

Why is this a big deal? Because 90% of the macro seminars I attend, at conferences and universities around the world,  still assume that the labor market is an auction where anyone can work as many hours as they want at the going wage.  Why do we let our students keep doing this?

A model is a tool for better understanding the world.  While there may be problems where this particular simplification allows complex estimation, when labor markets (e.g. unemployment) is a major target of inference this simplification seems to remove the most interesting variation (e.g. employment friction and how it makes fast job changes undesirable all around). 

Clearly, if this is the state of the art, these models could be improved (heck, even an employment change penalty function would do wonders). 

Sometimes, the SAT you read about in the news doesn't look much like the actual SAT

[Unless otherwise noted, 'SAT' refers to the SAT Reasoning Test]

There are real concerns about the SAT. The emphasis on vocabulary can and sometimes does create a problem with cultural bias and the test has a history of being misused, as do most psychometrics. Though it is possible to make too much of these abuses, we should remember that, like the IQ test, people have and in a more subtle fashion, continue to use tests like the SAT to make racist arguments.

But while there are valid arguments for changing, deemphasizing, or even eliminating the SAT, these are not the arguments you will see in the anti-SAT editorials in Esquire or the New York Times. Instead, we get attacks on an SAT test that doesn't actually exist (Though it quite possibly may after David Coleman is finished with his reforms).

Though it has long tried to live down the fact for various reasons, the SAT was designed to be what its original name suggests, a scholastic aptitude test. It was also designed to be largely orthogonal to GPA and other information found in high school transcripts. (you can find a more detailed discussion of this point here and here)

In order to achieve that orthogonality the SAT test to be written in such a way that students have taken more advanced classes do not have an unfair advantage. Partly for that reason, the SAT is perhaps unique among major measures of academic accomplishment in that it has almost no rote memory component other than vocabulary.* (From here on out, I am going to focus primarily on the mathematics section though most of the general comments will apply to the entire test.)

An old professor of mine, Bill Condon, once described the analytic SAT as the toughest ninth grade math test you will ever take. That's an extremely apt way of putting it. All of the mathematical concepts are either common sense or things which a ninth grader should have covered. Almost all of the rules and formulas needed for the test are printed in the front of the booklet.

The trouble with coverage of the SAT and to a slightly lesser extent the ACT is that virtually everyone whom you will find discussing it in the pages of a major newspaper or magazine has intense but old and usually highly unreliable memories of the test. Add to that the generally poor quality of the emotionally-charged education reform debate and the result is an incredibly unproductive discussion.

For a  representative example, check out this opinion piece written by Jennifer Finney Boylan for the New York Times, which puts the trauma front and center starting with the first sentence:

I WAS in trouble. The first few analogies were pretty straightforward — along the lines of “leopard is to spotted as zebra is to striped” — but now I was in the tall weeds of nuance. Kangaroo is to marsupial as the giant squid is to — I don’t know, maybe D) cephalopod? I looked up for a second at the back of the head of the girl in front of me. She had done this amazing thing with her hair, sort of like a French braid. I wondered if I could do that with my hair.

I daydreamed for a while, thinking about the architecture of braids. When I remembered that I was wasting precious time deep in the heart of the SAT, I swore quietly to myself. French braids weren’t going to get me into Wesleyan. Although, in the years since I took the test in the mid-’70s, I’ve sometimes wondered if knowing how to braid hair was actually of more practical use to me as an English major than the quadratic equation. But enough of that. Back to the analogies. Loquacious is to mordant as lachrymose is to ... uh ...

This was the moment I saw the terrible thing I had done, the SAT equivalent of the Hindenburg disaster. I’d accidentally skipped a line on my answer sheet, early in that section of the test. Every answer I’d chosen, each of those lines of graphite-filled bubbles, was off by one. I looked at the clock. Time was running out. I could see the Wesleyan campus fading before my eyes.

High school is a trauma-filled time and its humiliations and disappointments can stay fresh for decades as they obviously have here. They do not, however, often lead to objective or accurate analyses. It may well have seemed unfair at the time to be judged on knowledge of relatively obscure words, but given that vocabulary tracks fairly well with reading ability, it doesn't seem unreasonable to ask a future English major to display an understanding of words like 'loquacious,' 'mordant' or even 'cephalopod.' As for the math section, I assume from the definite article that "the quadratic equation" refers to the quadratic formula. If so, that's an interesting choice because that formula does not appear on the SAT.

The math that does appear on the SAT relies on the following:

properties of numbers;

basic algebraic manipulation;

very basic (junior high level) geometry (with relevant formulas printed on the first page);

simple probability;

reading graphs and tables;

logic and problem-solving.

All of these fall into the good-to-know category for the general population and I'd argue the last is especially valuable for English majors (bad logic makes for bad literary criticism and often bad literature).

Boylan then goes on to complain that the SAT relies too much on memorization and to argue for the superiority of high school GPA as an academic metric. As mentioned before, the rote learning component of the SAT is extraordinarily small, far smaller than the corresponding component for almost every test-based grade a student will receive in junior high and high school.

This oddly self-defeating argument "We should drop the SAT because it's too ____; instead, we should rely more on grades/other tests/whatever (which happen to be more _____ than the SAT)" also features prominently in a less personal but much less coherent piece by Esquire.com news editor Ben Collins. Collins' argument consists of a series of largely arbitrary but highly emotional associations (it's not entirely clear why he makes these connections but he certainly feels strongly about them).

The first and possibly strangest of these associations involves Google.

Google, a company that evolved from a search engine into the world’s de facto incubator for great ideas that define our future, does not look at standardized tests when they hire applicants. They don't look at whether or not an applicant went to a Holy Grail of the standardized test lottery -- an Ivy League school -- either.

The wording here is somewhat unclear (this almost sounds like the company redacts the education sections from applicants' resumes), but I know that the big players like Google are very interested in students coming of top computer science programs like the UC schools and particularly Stanford. Take a look at this SAT breakdown for the school that produced Google:

Score	Percent of Applicants	Admit Rate	Percent of Admitted Class
800	15%	10%	25%
700–799	45%	7%	54%
600–699	28%	4%	19%
Below 600	12%	1%	2%

Keep in mind that these numbers include humanities majors.  The graduates that a company like Google are interested would almost all be in the first two bins. Google doesn't talk much about SATs at least in part because they've largely maxed out the metric.

Collins' piece actually gets worse from there.

All of that is antithetical to the dog-eat-dog, score-high-at-all-costs test-taking culture that America has distilled in its young people. And all of that is exactly why Google is the most futuristic corporation on this planet.

They know that this kind of ingenuity and collaboration — not just knowledge — is what makes a smarter world. It is also what makes better people.

We have ritually and ceaselessly sucked the fun and wonder out of learning in a country that is pushing kids into adulthood aimless, goalless, robotic and depressed as a way to feed a system that we now know does not work.

Then we blame the adults for questioning the intent of that system, even when there is none.

Do not mistake a less-tested America for an Everybody Wins America — an academic extension of those soccer games where nobody keeps score. We need to keep score to stay competitive, to remark on ingenuity and encourage drive, to understand where help is needed and where greatness needs to be challenged further.

But we don’t need to do it in this increasingly antiquated, old-world way, a holdover from when we knew much less about our kids’ biology, how they learn, and how to compel them to be better.

Currently, we have our kids fill in bubbles, and if those kids fill in the bubbles wrong on a forgotten Saturday morning when they are 17, they’re cast to a lower lot for the rest of their lives.

This cannot be the American ideal.

Make no mistake: The next revolution is not another industrial one or another technological one but it will be our first educational one. America can lead the pack if it gets over its hubris, identifies and changes its faults, and unshackles itself from the tyranny of rules and routine that exist only for the sake of themselves.

Why try to play catch up with the old world when the greatest companies in the new economy are already here, in this country, creating new ways to make the world better? These companies are disregarding the rest of the world’s urge to retrofit an exponential stream of new information into a few hundred bubbles on a thin, white sheet of paper.

Only those kinds of companies are forging our future. Why don’t our kids deserve to be taught the same way?

China has better test scores across the board than the U.S. They do not have Apple or Facebook or Microsoft or Google. They do not have our ingenuity. Let’s start appreciating it, rewarding it, fighting for it. Let's start drilling a love of learning into the brains of our kids, in the place where fear and anxiety currently reside.

Where to start...

In some parts of this passage, Collins seems to be talking about some tests other than the SAT such as the PISA exams when addressing China** or VAM-based tests when discussing the effects on learning.  If this had led up to a condemnation of tests in general the conflation might be at least internally consistent, but with the paragraph about the importance of keeping score that possibility goes out the window. We have to limit his criticisms, however odd, to the SAT.

The only real specific Collins offers about why the SAT should be singled out for elimination is that the test is old. That's partially true. The test has constantly evolved, driven by some of the best and most sophisticated analytic techniques in the field, but in terms of the test's format and its role in the education system, we've had the current set-up since 1930.

I'd argue that the country has had a pretty good run of innovation since 1930 and while I wouldn't claim that the SAT was a major driver, it would be difficult to argue that it held us back. Collins seems to agree on the first part but he takes a strange turn from there. As best I can make it out, he's arguing that America is the most innovative country in the world so it's essential that we drop a major, longstanding component of our education system or we'll become like China.

All snark aside, we probably should have a good debate about the way college admissions work and about the (I think misplaced) emphasis we have come to put on getting into the 'right' schools. Unfortunately, writers like Boylan and Collins aren't contributing to that debate; they're just supplying misplaced anger and emotional baggage.

*There's a big question (too big to address here) about the role of vocabulary in the SAT. Ideally there should be no rote learning element here at all. The vocabulary component is supposed to measure things like how reading volume and comprehension. Memorizing lists of words is, in a sense, cheating; it's also of questionable effectiveness compared to good, active reading habits.

** From China Daily:

The first annual report on the SAT performance of Chinese students found the average score was 1,213 points out of the total of 2,400, some 296 points lower than US students and 337 points lower than the benchmark set by College Board, the organizer of the test.

The gap is mainly derived from the reading and writing parts of the test. Chinese students scored 170 points less than US students in the reading part, which reveals Chinese students lack training in critical thinking, according to the report.

Chinese students, known to excel in mathematics, earned 547 points out of the total of 800, only 30 points higher than US students. The report attributed the lower-than-expected performance to Chinese students' poor knowledge of English mathematical terms and the test is aimed at a junior level which is easier for US students.

Professional Conduct

Dean Dad has the best view on the Nazareth College decision to rescind a job offer for a philosopher:

I understand the emotional appeal of rejecting someone before she rejects you.  It’s psychologically healthy to outgrow that phase.  Yes, it’s frustrating when a candidate you’re trying to hire comes in with unrealistic requests.  But sometimes grownups have to power through the disappointment.  Here’s a phrase I’ve used in turning down unrealistic requests:

“No, sorry, I can’t do that.”

 It would have likely accomplished the same outcome, without the chilling effect on future negotiations at the college.  Colleges have a great situation for hiring in fields like philosophy and it is likely that a much better fit could easily be found. 

Problems with modern reform paradigm

If this is correct then I see a potential problem with school (charter or not) use of standardized tests:

Parents don’t want their children’s teachers evaluated on the basis of student standardized test scores because they know it is unfair.
– Encouraged by the Obama administration, states now have teacher and principal evaluation systems that include test scores. Unfortunately, many teachers wind up being evaluated on the scores of students they don’t have or subjects they don’t teach.
Parents want to see their child’s standardized tests after completion.
– They can’t. The tests are proprietary.

Now remember that no instrument is perfect. But under what conditions does it make sense for the tests used to evaluate teachers not be made public?  What if there was an error? 

If evaluation is really the goal and we want to make data driven decisions, then are not the testing instruments themselves an important part of the environment?  Nobody would trust me to publish data from a Epidemiological study where there were not publically available instruments and public access data sets. 

Just look at the value that making NHANES public has generated.  Why should we not foster the same openness in education that has been so successful in public health? 

When threads collide -- David Coleman vs. Prof. Feynman

In all the coverage and controversy over the recent changes in the SAT, one of the aspects that troubles me the most is the one that seems to bother most people the least (emphasis added):

[David] COLEMAN: The new math section will focus on three things: Problem solving and data analysis, algebra and real world math related to science, technology and engineering fields.

The response from most journalists and pundits to this push for applicability has been either disinterest or mild approval, but if you dig into the underlying statistics and look into the history of similar educational initiatives, it's hard not to come away with the conclusion that this change pretty much has got to be bad (with a better than even chance of terrible).

The almost inevitable bad outcome will be the nearly unavoidable hit taken by orthogonality. As discussed earlier, the value of a variable (such as an SAT score) in a model lies not in how much information it brings to the model but in how much new information it brings given what the other variables in the model have already told us. Models that colleges use to assess students (perhaps with trivial exceptions) include courses taken and grades earned. We want additional variables to that model to be as uncorrelated as possible with those transcript variables. The math section of the SAT does this by basing its questions on logic, problem solving and on basic math classes that everyone should have taken before taking the SAT. Students whose math education stopped at Algebra I should be on a roughly equal footing with students who took AP calculus, as long as they understood and retained what they learned.

Rather than making the SAT a more effective instrument, "real world" problems only serve to undercut its orthogonality. Meaningful applied questions will strongly tend to favor students who have taken relevant courses. It might be possible to avoid this trap, but it would be extremely difficult and there's no apparent reason for making the change other than the vague but positive connotations of the phrase. (It's important to note here that Coleman's background is in management consulting and the ability to work positive-sounding phrases into presentations is very much a core skill in that field.)

Even more worrisome is the potential for the really bad question, bad enough to have the perverse effect of actually causing more problems (in stress and lost time) for those kids who understand the material. Nothing throws a good student off track worse than a truly stupid question.

Even if the test-makers know what they're doing, writing good, situation-appropriate problems using real situations and data is extraordinarily difficult. The vast majority of the time, real life has to be simplified to an unrealistic degree to make it suitable for a brief math problem. The end result is usually just an old problem with new nouns, take a rate problem and substitute "computer programmer" for "ditch digger."

You can make a fairly good case for real world questions based on teaching-across-the-curriculum -- for example, using Richter scale in a homework problem is a good way of working in some earth science -- but since the purpose of the SAT is to measure, not to instruct, that argument doesn't hold here.

The even bigger concern is what can happen when the authors don't know what they're doing.

From Richard Feynman's "Judging Books by their Covers":

Finally I come to a book that says, "Mathematics is used in science in many ways. We will give you an example from astronomy, which is the science of stars." I turn the page, and it says, "Red stars have a temperature of four thousand degrees, yellow stars have a temperature of five thousand degrees . . ." -- so far, so good. It continues: "Green stars have a temperature of seven thousand degrees, blue stars have a temperature of ten thousand degrees, and violet stars have a temperature of . . . (some big number)." There are no green or violet stars, but the figures for the others are roughly correct. It's vaguely right -- but already, trouble! That's the way everything was: Everything was written by somebody who didn't know what the hell he was talking about, so it was a little bit wrong, always!

Anyway, I'm happy with this book, because it's the first example of applying arithmetic to science. I'm a bit unhappy when I read about the stars' temperatures, but I'm not very unhappy because it's more or less right -- it's just an example of error. Then comes the list of problems. It says, "John and his father go out to look at the stars. John sees two blue stars and a red star. His father sees a green star, a violet star, and two yellow stars. What is the total temperature of the stars seen by John and his father?" -- and I would explode in horror.

Keep in mind, Feynman's example was picked to be amusing but representative ("That's the way everything was...a little bit wrong, always"). The post-Sputnik education reformers of his day were making pretty much the same demands that today's reformers are making. There's no reason to expect a better result this time.

Of course, there are good questions that do use real-world data (you can even find some on the SAT), but in order to write them you need a team that understands both the subtleties of the material and the statistical issues involved in testing it.

The more I hear from David Coleman, whether it concerns the College Board or Common Core, the less confidence I have in his abilities to head these initiatives.

Differential growth in life expectancy?

There has been a lot of discussion about Annie Lowrey's article on changes in life expectancy, documenting how most of the recent rise in life expectancy is among Americans of higher socio-economic status.  I did find the question of causality to be less compelling:

It is hard to prove causality with the available information. County-level data is the most detailed available, but it is not perfect. People move, and that is a confounding factor. McDowell’s population has dropped by more than half since the late 1970s, whereas Fairfax’s has roughly doubled. Perhaps more educated and healthier people have been relocating from places like McDowell to places like Fairfax. In that case, life expectancy would not have changed; how Americans arrange themselves geographically would have.

“These things are not nearly as clear as they seem, or as clear as epidemiologists seem to think,” said Angus Deaton, an economist at Princeton.

It is possible that there is a process of re-arrangement going on.  But that still doesn't make charts like the second one in this Aaron Carroll blog post easier to explain.  If the higher earning recipients of social security live longer than the lower earning recipients, then this association is not simple to explain with a direct appeal to the ecological fallacy. 

This is the sort of case where data is limited but we still need to make decisions.  It is odd that with some decisions we are desperately worried about getting things wrong when it advantages the affluent but we seem quite worried about over-interpreting data when redistribution would be the obvious policy solution. 

“The best thing that happened to the education system in New Orleans was Hurricane Katrina”

Joseph has already commented on one aspect of this Valerie Strauss article on Netflix CEO Reed Hastings, but a different passage caught my eye.

He appears to be presenting a vision of education in the United States where nearly all students are educated in collections of charter schools: “So what we have to do is to work with school districts to grow steadily, and the work ahead is really hard because we’re at 8% of students in California, whereas in New Orleans they’re at 90%, so we have a lot of catchup to do.”

As indicated by the Arne Duncan quote I used as a title, the notion of New Orleans as the educational ideal is strongly established in the reform movement. New Orleans has implemented the major tenets of the reform pedagogy to an extraordinary degree, particularly the rigid, metric-driven, no-excuses attitude. On this much, everyone can pretty much agree.

When we get to effects, however, the picture gets murkier. There has been some improvement in test scores but the 'reforms' coincided with increased spending which would be expected to boost scores. In addition, some of the increase can also be assigned to considerably increased pressure of students to take the tests seriously. Even putting all that aside, the improvements still don't look that impressive when compared to demographically similar schools in other states. Bruce Baker of Rutgers did the heavy lifting.

The bigger story for me, though, is in the details of the now dominant culture of New Orleans schools and in how parents and students have reacted.to the new regime. It's apparent that quite a few people are extremely unhappy.

A previous post mentioned students from one New Orleans high school walking out in a mass protest.



This was not an isolated incident.

Sci Academy, the flagship of the Collegiate Academies charter group, is known for high test scores and stringent discipline policies, such as requiring students to walk between lines taped on the floor. School leaders say the two go hand-in-hand: You don't have to walk on the right side of the hallway in college, but the discipline will serve you well.

But students at the group's two new schools, George Washington Carver Collegiate Academy and George Washington Carver Preparatory Academy, walked out the week before Thanksgiving, angry about such rules. On Wednesday (Dec. 18), about 60 students attended a rally. A letter of demands written by some students said kids were being suspended "for every little thing."

Recent state data show there are grounds for that claim. The three Collegiate schools had the city's highest suspension rates in the 2012-13 academic year. A full 69 percent of Carver Collegiate's student body was sent home at least once. Carver Prep suspended 61 percent of its student body. Sci Academy sent home 58 percent, a 9-point increase from the year before.

Anyone with experience with K-12 education can tell you that mass suspension and expulsion may possibly be the simplest and most effective way of improving test scores and making classroom management easier (a particularly pressing issue if you have high teacher turnover and rely heavily on programs like TFA). The problem with the technique is that it takes its greatest toll on the most vulnerable students. To fully grasp the brutality of these methods, you have to look at specific examples, such as this one from a parents' advocate in New Orleans:

The case that still breaks my heart involved a 14-year-old who kept getting demerits because his uniform shirt was too small and came untucked basically every time he moved. His mother was a veteran, well-educated, and had sold real estate but got divorced and ended up losing her job, and became homeless. They were living with friends and really struggling. The school expelled the child because he’d had three suspensions—the last one for selling candy to try to raise enough money to buy a new shoes and a new uniform shirt. I felt that if the mother went and told her story that the school would understand and wouldn’t hold up the expulsion. She didn’t want the school to know how impoverished she was but I convinced her to do it, so she came and told all of these people what she was going through—about her struggles. I thought for sure the board would overturn the expulsion, not just because her story was so compelling, but because there wasn’t actually anything in the school’s discipline book about selling candy. But they upheld it and it broke my heart that this kid was being put out of school because he was poor.

I don't know if this student went to one of the specific schools discussed here, but I can tell you that this is all too often what the process looks like, which is why responsible administrators use it so reluctantly.