Stop me if you've heard this one before

Michael Shermer has an interesting post over at Scientific American, but there's one paragraph I'm not too happy about.

Cognitive dissonance may also be at work in the compartmentalization of beliefs. In the 2010 article “When in Doubt, Shout!” in Psychological Science, Northwestern University researchers David Gal and Derek Rucker found that when subjects' closely held beliefs were shaken, they “engaged in more advocacy of their beliefs ... than did people whose confidence was not undermined.” Further, they concluded that enthusiastic evangelists of a belief may in fact be “boiling over with doubt,” and thus their persistent proselytizing may be a signal that the belief warrants skepticism.

I'm way out of my field on this one. My knowledge of psychology is limited to an undergrad intro course and a copy of Cialdini's Influence, but I'm pretty sure that researchers have been finding this sort of thing since the mid-Fifties when Leon Festinger wrote about doomsday cultists proselytizing more the day after the world failed to end and confirming this and related aspects of cognitive dissonance ever since in a large group of studies. (Discover did a better job with the context, though that is comparing a paragraph to a whole post.)

I don't mean to suggest Gal and Rucker were not doing important, original work. I'm sure they were. My beef here is with Shermer and the lack of context. A reader coming on this paragraph cold would be left with the impression that this was a new idea rather than the latest brick in a decades long wall.

I can understand the appeal of the cutting edge. The new stuff is sexier. It gets people's attention. The trouble is, those cutting edge studies often collapse under scrutiny. Some can't be replicated. Others prove to be not that important.

Confirmation, on the other hand, is not sexy. It doesn't drive traffic. It's harder to fit into a paragraph. In a way, though, it's more interesting because it has a high likelihood of being true and fills in the gaps in big, important questions. The interaction between the ideas is usually the interesting part.

Of course, this may be awfully picky given that we're talking about a single paragraph, but this is a recurring issue. New developments are frequently reported in a vacuum, and the result is often a badly misled reader. In these situations a few lines of context can go a long way.

Misleading graphics

This infographic has been coming under criticism from the usual suspects.  The group that got hit the worst was the married couple with two children making $650,000 per year.  According to the census bureau, in 2009 the median income for a household was $49,777.  So there is a tax increase of 3.3% on couples making 13 times the median US household income. 

Needless to say, this really doesn't reflect the likely impact of these tax law changes on the typical American (it is just to easy to ask hard questions about the representativeness of a single mother who makes $260K/year). 

[note -- label typo corrected]

More thoughts on Education

A couple more thoughts on the whole education reform movement, both hoisted from comments.

First, there was a comment by Stuart Buck:

As a matter of basic social science, what should concern one is not the absolute level of a state's performance now but the counterfactual (what would its performance otherwise be).
 

This is absolutely correct.  However, what we are really missing is a time frame for improvement as well as an expected magnitude of improvement.  So if we look at 1999, the top rated state in StudentsFirst (La) had a Grade 8 reading score of 252 (compared to an average of 261).  In 2011 the score was 255 (improved 3 points) versus a national average of 264 (which also improved three points).  Between 2009 and 2011 both La and the national average also improved by the same amount.  DC is even more interesting.  In 2007 (when Rhee began her reforms) Grade 8 reading was 241 (versus 261 nationwide).  In 2011 it was 242 (versus 264 nationwide). 


So we would have to explain the unexpected drop in performance we expected in Louisiana that simply did not happen or the reason by DC lagged even further 4 years into a reform program.  Even longitudinally, first in the nation seems odd given a lower baseline (thus more room for improvement due to lower hanging fruit and maybe even regression to the mean) and an absolutely dead standard increase. 

Second, at lawyers, guns and money a commenter said:

That being said, using it for evaluative purposes is misguided and unfair to educators. I proctor the test, and I see a large number of students who don’t take the test seriously at all. They just click through to get it over with. Our student population has taken the test in the grips of a horrible flu outbreak. Those kids who were actually in school at the time were sick, getting sick, or struggling to get over being sick. When you have to spray down the computers with Lysol after every class comes through, you really have to question the validity of the results obtained. Technical difficulties that require restarting the computer and/or test can also have a suppressive effect on students’ scores.
 

As the Tech coordinator in a school, this seems to be a reasonable position to make such an evaluation.  That raises the question of "high stakes for whom"?  I am actually a fan of looking at SAT scores.  Why?  Because not only is the test well respected but the test makers have a financial incentive to make sure the test does what they say it does (so it can continue as a national standard).  The students have an incentive to do well on this test because high scores open doors for them.  So when a teacher is evaluated on SAT performance, I am pretty comfortable saying that the other actors are likely to have aligned incentives on giving an unbiased estimate.

Finally, the thing that really seems to be mixed up in the Rhee report is the difference between efficiency (cost savings) and quality (performance).  By analogy, consider military pensions.  They exist, in large part, so that we can retain top performers in the armed forces.  If anything the defined benefit pensions improves quality by keeping soldier with 15 years of valuable experience in the military.  The problem with pensions only arises if the military gets bad at weeding out incompetent performers (which, so far as I can tell, is not currently a major problem).  It is good to keep experienced people around while they are still effective but it is expensive.  So the empirical question is does it cost more than it is worth?

The same issue arises with the class size metric.  I have been in large and small classes with an excellent teacher.  I learned a lot more in the small class because the teacher could focus more attention on each student.  Is it better to have large classes (like StudentsFirst claims)?  Well, only if you have identified top performers and can assure yourself that you are compensating for class quality with teacher quality.  This is a hard claim to support.  On the other hand, almost no luxury is as expensive as small classes.  Notice how universities have reacted to this pressure by putting hundreds of students into a single classroom.  So is the cost worth the improvement in quality is a legitimate question. 

So the issues here are twofold.  One, the data on performance do not seem to map easily onto the counter-intuitive rankings of StudentsFirst.  Two, the type of high stakes test that seems to be a key feature of the education reform movement has some work to do in properly aligning incentives. 

 

Hat tip to Yglesias

Mark and I have been hard on Matt Yglesias lately.  But this post was a really clever idea.  He took Kevin Drum's idea that lead was responsible for a rise in violent crime and asked "if this explanation is correct then what else must be true?".  Since impulse control is also linked to high school graduation he plotted high school graduation (which has been unexpectely rising) and sees the same pattern as with violent crime. 

Now nothing rules out a confounder that affects both of these outcomes.  I worry about simple explanations for complex phenomena.  But it was a clever idea to try and falsify the hypothesis by looking at things that should be related to violent crime.  And, if there was going to be a candidate for such a broad level of toxicity, a substance implicated in brain damage going back to classical Rome isn't a bad choice. 

Felix Salmon on personal finance

Felix Salmon has beaten me to the punch here but I do think that this statement needs to be properly understood for what it means:

It surely comforts modern parents who have spent fortunes educating their children to know that these children are spending money on pork belly and not, for instance, cocaine. But what solace can it offer to realize that $300 a week put into an S. & P. 500 Index fund over the past five years would have provided an annual rate of return of 10.34 percent and grown to $100,354 today? Even saving $300 a week at a 6 percent rate of return would have yielded about $91,000, Mark X. Chemtob, a financial adviser at Ameriprise, said, adding that in both cases, the sums would qualify for a down payment on a starter apartment in New York.

So if a person invested for five years, and got a retern of 10.34 percent they would have a lot of money.  So have happened 5 years ago (2007)?  Here is wikipedia:

The Dow Jones Industrial Average, Nasdaq Composite and S&P 500 all experienced declines of greater than 20% from their peaks in late 2007. 

So if you had perfect market timing then you could have invested directly after a crash (as opposed to during it) taking advantage of the recent market crash.  Unless, of course, you were the 23 year old in the article who is likely in school and not making $300/week of investable income. 

The other side of this coin is that it is very hard to be 23 years old, just graduated from school, making real money for the first time in your life and not enjoy some of it.  After all, perpetual deferred gratification is never being able to enjoy the rewards of your career.  Nor is it clear that somebody in their first year out of college should be buying a Manhattan apartment (a highly leveraged investment) until they find out if they are going to be successful in New York. 

Nor can you drop the cost to zero.  I would find it hard to eat in New York city for less then $75/week.  Remember, we are taking a city where space is at a premium and everything bought in the city is expensive (including kitchen facilities).  So eating 21 meals at about $3 apiece is actually pretty tough, even if you have good skills for cooking from scratch.  And, even more interesting, the person in this example is taking on extra work to fund her leisure time (as opposed to, for example, debt). 

So I agree -- a very misleading example. 

Technological stagnation bandwagon

Looks like this idea may actually be getting fashionable (from the Economist):

So it may come as a surprise that some in Silicon Valley think the place is stagnant, and that the rate of innovation has been slackening for decades. Peter Thiel, a founder of PayPal, an internet payment company, and the first outside investor in Facebook, a social network, says that innovation in America is “somewhere between dire straits and dead”. Engineers in all sorts of areas share similar feelings of disappointment. And a small but growing group of economists reckon the economic impact of the innovations of today may pale in comparison with those of the past.

Now we just have to figure out what to do about it.

Matt Yglesias -- Defending the indefensible

[I've been off line most of the week so instead of participating in the discussion on the Students First report card, I am, with apologies for the length, putting down my reaction in one big, ugly lump]

At some point in the past year, it became impossible to mount a serious defense of Paul Ryan. There had always been cracks in the facade -- numbers that didn't add up, unlikely claims, extremist quotes -- but most of these could be ignored and those that couldn't were invariably excused that Ryan was sincere, he was a serious budget guy and he was getting us to discuss important policy questions.

Eventually though, the discrepancies started to accumulate, and by the time we got the specifics (or non-specifics) of the Ryan budget and the close scrutiny of the campaign, the standard excuses simply weren't sufficient. This left a large number of journalists with a difficult choice: distance themselves from a politician they had invested great emotional and reputational capital in; or invest still more in increasingly strained defenses. The most memorable example of the first was William Saletan's amusing break-up letter. The most embarrassing example of the second probably comes from James Stewart.

In many ways, Michelle Rhee has occupied a Ryan-like niche in the education. Both started out as camera-friendly media darlings with highly marketable bipartisan appeal and reputations as serious problem-solvers. In both cases there were, from the beginning, troubling details that undercut these reputations but at the time these details never got much traction. As with Ryan and fiscal responsibility, criticizing Rhee was often read as indifference towards the education gap.

But, as they did with Ryan, nagging questions started to accumulate. There were incidents that seemed to show Rhee abusing her authority. There were questions about cheating under her watch. There was increasingly pointed anti-teacher rhetoric. There was the aggressive pursuit of self-advancement.  At each stage, more of Rhee's liberal supporters started getting uncomfortable.

For many, such as the New Republic's Seyward Darby, the tipping point came when Rhee partnered with Florida's Rick Scott. Before Scott, Rhee's liberal supporters had taken the position had been that she was tough on teachers, but reluctantly, and only because it was necessary in order to improve education. With Scott these outcomes were reversed. He was willing to pursue a "reform" agenda if it hurt a faction he saw as hostile.

The alliance with Scott and similar figures alienated some supporters on the left, but it still allowed the possibility that Rhee was acting in good faith. With the release of the Students First state report card, even that is gone. There is not even a pretense that this is about anything other than promoting Rhee and her allies. The Washington Post had a good summary.

In Rhee’s grading system, the D.C. school system that is implementing the reforms she instituted got a higher grade than the states of Maryland and Virginia — which consistently are at or near the top of lists of high-performing states — and Virginia. Maryland got a D-plus. Virginia got a D-minus. The District? The urban system with the highest achievement gap in the country? It got a C-plus. 

The states that got the highest score handed out — a B minus — were Florida and Louisiana. No surprise there.

Florida’s reform efforts were spearheaded more than a decade ago by then-Gov. Jeb Bush, who was the national leader in these kinds of reforms. The school accountability system that Bush set up, the Florida Comprehensive Assessment Test, is scandal-ridden, but he still travels the country promoting his test-based reform model.

Louisiana is the state where Republican Gov. Bobby Jindal instituted a statewide voucher program that gave public money to scores of Christian schools that teach Young Earth Creationism, the belief that the Earth and the universe were created by God no more than 10,000 years ago. Kids learn that dinosaurs co-existed with humans. That’s the state that got Rhee’s top grade.

A quick digression on some good indicators of when a metric has been cooked:

1. It reaches an unexpected, even unbelievable conclusion in the favor of the person designing the metric;

2. It leaves out important variables;

3. And leaves in other variables only tangentially related to the central question;

4. It uses an odd, difficult to justify weighting scheme, making certain factors dominant for no apparent reason.

This report is not only cooked till it's charred; it also flies in the face of Rhee's own rhetoric on tests and accountability. It is, in a word, indefensible, but just as Ryan had James Stewart, Rhee has Matt Yglesias.

Michelle Rhee is a controversial figure, and anything her advocacy organization, Students First, does is going to attract a lot of derision. But having had the chance to play around with their "report card" on state policy, I think there's a lot to like here.

The best thing about it, really, is just that they did it. Importantly it's a report card assessing the state of education policy in different places, not outcomes. ... Only two states score above C+ on their ratings—Louisiana and Florida—and student learning outcomes in those states are far from the best in the nation. If Louisiana starts making a lot of progress in closing the gap with, say, Maryland, then that'll be powerful evidence for the Students First approach. But if it doesn't, then you get the reverse.
...
In policy terms, the most interesting thing about the Students First report is probably its treatment of charter schools. ... The Students First perspective more wisely dings states that make it too hard to open charters but also dings states (like, say, Arizona) that do much too little to hold charter schools accountable for performance.

You should probably read the whole thing (it's less than 300 words) but this gets at the gist. The entire piece is pretty much just a pander and two short, flawed arguments.

Let's start with the "powerful evidence" argument. Yglesias here treats the report card as not really being a measure of school quality (he doesn't have much choice since the score is actually inversely related to school quality), rather a measure of where schools fall on a policy spectrum so we can basically treat their score as an independent variable when evaluating these policies by comparing score with improvement.

It's worth noting that Rhee's site introduces the report card as follows "We hope this helps reveal more about what states are doing to improve the nation’s public education system so that it serves all students well and puts each and every one of them on a path toward success." Here and elsewhere, Rhee clearly means that the states with better scores are doing a better job. This doesn't align very well with Yglesias's argument.

More to the point though, the argument doesn't hold up even in isolation. The idea of providing a useful indicator would only make sense if we scored the schools at the beginning of implementation of the policies. Instead we have a collection of initiatives with varying start dates, most a few years old, some dating back to Jeb Bush. Perhaps as bad, Yglesias leaves the time frame open (always a bad idea) in a situation where a shake-up in the achievement rankings for any reason will tend to favor states at the top of the Students First list. (Louisiana can't really go that far down.) Any kind of causal inference drawn from a change in one of these top scored states would be meaningless.

The only other specific Yglesias can come up with is that the report supposedly requires schools to hold charter schools accountable for performance. Putting aside the obvious "accountable for performance" irony, this claim is a bit difficult to accept at face value given the related question of holding private institutions that receive state money accountable. Remember, Louisiana is Rhee's top ranked state despite a voucher system notorious for its lack of accountability:

The school willing to accept the most voucher students -- 314 -- is New Living Word in Ruston, which has a top-ranked basketball team but no library. Students spend most of the day watching TVs in bare-bones classrooms. Each lesson consists of an instructional DVD that intersperses Biblical verses with subjects such chemistry or composition.

The Upperroom Bible Church Academy in New Orleans, a bunker-like building with no windows or playground, also has plenty of slots open. It seeks to bring in 214 voucher students, worth up to $1.8 million in state funding.

At Eternity Christian Academy in Westlake, pastor-turned-principal Marie Carrier hopes to secure extra space to enroll 135 voucher students, though she now has room for just a few dozen. Her first- through eighth-grade students sit in cubicles for much of the day and move at their own pace through Christian workbooks, such as a beginning science text that explains "what God made" on each of the six days of creation. They are not exposed to the theory of evolution.

"We try to stay away from all those things that might confuse our children," Carrier said.

Other schools approved for state-funded vouchers use social studies texts warning that liberals threaten global prosperity; Bible-based math books that don't cover modern concepts such as set theory; and biology texts built around refuting evolution.

That's it. Out of the "lot to like" here, Yglesias can only come with a flawed we-can-see-how-we're-doing argument and a highly suspect claim about accountability. Less than three hundred words total and he's clearly scraping bottom to put those together.

This whole affair is a case study in how bad ideas lodge themselves in the discourse through journalistic convergence and superficiality, the fetishizing of balance, and the inability of otherwise smart, responsible people to admit (perhaps even to themselves) that they've been proven wrong.

update: link added.

Sometimes I need to read more clearly

I had noted that the presence of defined benefit versus defined contribution pension plans in the evaluation of state education systems.  This was obviously hard to fathom as the way you handle retired teachers seems to have limited predictive ability for the quality of education.  I had not realized it was an anchor category:

 Amazingly, the methodology being used by Rhee’s grifters gives states a “4″ (the highest score) if they have defined contribution pensions and a “0″ if they have defined benefit pensions. In other words, states get higher rankings for their education systems if they make their pension benefits less attractive! Even more amazingly, pension “reform” is an “anchor” category, meaning it gets three times the weight of some of the other categories that might actually have a clear positive relationship with improving a state’s educational system.

So even if you thought there was some small effect here (older teachers hanging on for a couple of extra years to improve their pensions who could easily have found a job elsewhere?), it's hard to imagine that this is a key metric that should be given special weight.

This sort of revelation really does point out the problem with models: bad data in, bad results out.  

Causal Inference

Andrew Gelman comments on an article linking genetic diversity (both high and low) with less economic performance than countries with middling levels of diversity.  His take-away is quite good:

High-profile social science research aims for proof, not for understanding—and that’s a problem. The incentives favor bold thinking and innovative analysis, and that part is great. But the incentives also favor silly causal claims. In many social sciences, it’s not enough to notice an interesting pattern and explore it (as we did in our Red State Blue State book). Instead, you’re supposed to make a strong causal claim even in a context where it makes little sense.
 

But I also think it omits one piece that is crucial for causal claims: what does a counterfactual look like?  This happens a lot with complex phenomenon in both medicine and social science.  Just look at the question of whether or not to adjust for variables like blood pressure and cholesterol when estimating the effect of obesity on mortality:

 It's possible that most of the thin people who die are meth addicts or have cancer, but even a study which threw out the folks who died within three years of entry into the study found that once you accounted for physical activity*, "underweight" BMIs were correlated with excess mortality risk, while "overweight" BMIs were not. And arguing that the study fails to control for things like blood pressure, blood sugar, and cholesterol seems like fairly weak sauce; those are the very mechanisms by which obesity is supposed to kill us. 
 

So what would it mean to make a person thinner and not influence the mediating factors through which the disease operates?  It would be a thin person with a lot higher risk of mortality, I suspect.  It's the same example as imagining an antihypertensive medication conditioned on blood pressure -- one would suspect that the causal effect of the drug on the participant would be different if it failed in its primary function. 

In the same sense, the question of how to change genetic diversity without influencing a lot of other variables is a tricky one.  What would it mean for a country whose genetic composition was unrelated to migration to change their level of diversity without changing other factors?  What is the mechanism by which we think this operates?  Mechanisms are not very important for randomized trials because the design eliminates confounding.  But for a non-randomized study, this is a very important piece.

And if we argue that this is just a proxy variables (which seems to be the route that Andrew is taking in his discussion)  then the hard causal claims are unecessary.  Even worse, they may well obscure factors on which we could imagine basing a strong counter-factual.  Exploring data like this is an extremely interesting exercise but I agree that I wish we could admit when we see an interesting pattern that we may not know why this pattern exists. 

Professors and stress

This reply to the classic Forbes article by Susan Adams is worth reading. My favorite piece:

Write a grant application, get three anonymous reviewer critiques. Submit research results for publication in a peer-reviewed journal, get anonymous reviewer critiques. Submit your tenure portfolio or post-tenure portfolio to a college promotion and tenure committee, get anonymous reviews. While one may know the general composition of grant review and promotion and tenure committees, you don’t know precisely who is gunning for you. Anonymity is sometimes useful but more often allows petty vendettas to occur that are independent of the work at hand.
 

It is amazing how true this can be and how hard it is to try and modify your approach based on feedback when the next set of anoymous reviewers could be completely different. 

Metrics on education

Matt Yglesias has a post up about the StudentsFirst report claiming that outcomes are complicated to measure.  While this point is, in the abstract, true, it is informative to see what the highest ranked state (Louisiana) does in the grade 8 reading tests results that he shows.  He gives a number of groups: Everyone, Africian American, Latino, Low income, and White.  Louisiana is in the below average group for all groups except Latinos (where they are average).  It is also worth noting that Latinos make up about 3% of Louisiana's population, whereas African Americans make us around 34% of the population.  So they get average results only in a very tiny minority population.

Now there are lot's of reasons why a school system might be doing the best that they can and student results are divorced from a lot of complex social phenomenon.  However, when the top ranked states is below average on most student outcomes and above average for no populations that should be concerning. 

Now maybe the reforms have been too recent to have results.  But if reforms have very long lag times then we have another problem -- how do we properly evaluate the quality of reforms if it takes a decade to be seen in the test results? 

UPDATE: See here for the actual correlation coefficients.  Consider:

Looking more rigorously at the results, the correlation coefficient on the rankings in the StudentsFirst report card with state rankings on reading scores is -0.20. (The correlation coefficient is a measure of the similarity of two sets of numbers, ranging from -1.0, completely dissimilar, to +1.0, perfect similarity.) That’s not a large number, but the negative sign means that the correlation is in the wrong direction: the higher the StudentsFirst score, the lower the NAEP reading score. The correlation on math is even worse, -0.25.

It's not a good sign when the outcomes data is in the wrong direction. 

EDIT 2: Missing link inserted

Charter school tricks: an ongoing saga

This is remarkable:

Boston’s Commonwealth charter schools have significantly weak “promoting power,” that is, the number of seniors is routinely below 60 percent of the freshmen enrolled four years earlier. looking at it another way, for every five freshmen enrolled in Boston’s charter high schools in the fall of 2008 there were only two seniors: Senior enrollment was 42 percent of freshmen enrollment. in contrast, for every five freshmen enrolled in the Boston Public Schools that fall there were four seniors: Senior enrollment was 81 percent of freshmen enrollment.

High graduation rates seem to be misleading if the weaker students are simply being pushed out and back into the public system (or even worse not in the system at all).  An honest conversation about choice requires that we be aware of the ways that private institutions are different than public ones.  I know people who have had their kids kicked out of a daycare because it wasn't working out and because a private institution can do what it wants with customers.  The ability to remove disruptive students is certainly a nice benefit, but does the likely arms race really work out for the children involved? 

Educational Performance?

StudentsFirst just released their state rankings.  You know who came in first?

Louisiana is the top-rated state, according to StudentsFirst. It ranks 49th of 51 on eighth grade reading scores and 47th of 51 on eighth grade math scores.

Washington, DC (dead last on NEAP scores) comes in 4th in the nation for educational performance as rated by StudentsFirst.  Now it is possible that these scores predict improvement in these states and that this is the result of bad past policy.

It's also interesting to see some of the categories.  Look at page 77 of the methodology report and see that they lower the rating of school system that restrict class sizes (bigger classes = better) and, even more interestingly, rate a state more poorly for having a defined benefit pension plan.  How does a defined benefit pension plan and the absence of class limits IMPROVE education.  I could imagine these being orthogonal to educational outcomes and thus argued to be options for fiscal improvement.  But it is hard to argue that they worsen student outcomes.

The Ddulite Bifurcation

From inappropriate aggregation to silly juxtapositions.

For the original definition of Ddulite check the link. For now it's sufficient to say we're talking about people (particularly journalists) who have an emotional, gee-whiz reaction to technology without really thinking seriously about the functionality.

Ddulite journalists can be spotted by a few defining characteristics: a remarkable ability to be impressed by the unimpressive; a focus on shiny, sexy toys; a tendency to report on technologies that really aren't that close as being just around the corner; a recurring amnesia about the slow development of similar technologies; general obliviousness to questions about implementation and demand; and what we might call the ddulite bifurcation.

The typical bifurcation consists of two applications of a new technology, one application mundane but realistic, the other impressive but so wildly ambitious that it may not even be theoretically possible with the technology being discussed.

I was going to make up an absurd example here but now that I think about it, I'm not sure I could do better than this actual story from Planet Money. The subject is 3-D printers and it's worth listening to.The Planet Money people are good, solid reporters and they do a reasonable job putting things in economic context, even bringing in Tyler Cowen to shoot down some of the more extravagant this-is-the-future claims.

But you can count on any story like this to have at least a few ddulite moments and you can certainly find them here, including this classic bifurcation. First we get this claim from a CEO named Pete Weijmarshausen:

Now, I think in a few years, we can print clothing, and then you can have clothing without sizes, but you have the size that fits you.

(Note the qualifiers here: "I think"; "in a few years.")

This is followed a few lines later by analyst Terry Wohlers saying:

WOHLERS: You lose a finger, you print out a new one.
CHACE: Yeah, like, actual body parts, printing out new fingers using your cells.
WOHLERS: Bones and bladders and eventually kidneys and so forth.

(glad he put the "eventually" qualifier with kidneys)

At the risk of belaboring the obvious and working under the assumption that most of you reading this know waaaay more about regenerative medicine and therapeutic cloning than I do, the day when we can easily grow new limbs is probably not just around the corner. Important fundamental research is being done and it's reasonable to talk about being able to do this someday but it could be a long way off. As for 3D printing approaches, we seem to be at the appears to be theoretically possible stage where we can work with masses of tissue rather than just a few cells by creating synthetic vascular systems.

This is exciting research but it's the sort of thing that's probably years away if it ever proves viable. Like most reporting about nanotech, the story mixes the ongoing with the theoretically possible in a way that obscures the huge gap between the two.

Professors and adjuncts -- inappropriate aggregation watch at Forbes

As a follow-up to Joseph's last post on this much-maligned piece from Susan Adams at Forbes, I'd like to add yet another complaint based on this bit from Adams' post:

As for compensation, according to the Bureau of Labor Statistics, the median salary for professors is $62,000, not a huge amount of money but enough to live on, especially in a university town.

Another boon for professors: Universities are expected to add 305,700 adjunct and tenure-track professors by 2020, according to the BLS. All of those attributes land university professor in the number one slot on Careercast.com‘s list of the least stressful jobs of 2013. 

As I've mentioned before, adjuncts have no job security and work very hard for little more than kind words and Pez (the median being a lot less than 62K). By jumping from a statement about professors to one about professors and adjuncts, Adams is using a variation on the rhetorical deception I call the cigarettes and cocaine argument.

"We just don't have the money for you to keep smoking. Do you realize that between your smoking and my cocaine habit we're spending more than two thousand dollars a week? You're just going to have to give up cigarettes."

The gold standard of the C and C argument is the ever popular case for Social Security reform that goes like this:

I. We have to do something about SS

II. The combined costs of SS and Medicare is projected to be more than a gazillion dollars in the red by twenty-whatever

III. That's why we need to cut/privatize/phase out SS

Of course this is just one of many problems in Adams' piece (as Joseph said, James Joyner does a great job addressing the major flaws here), but inappropriate aggregation is an embarrassingly large part of the public discourse and it supports any number of bad arguments and ill-conceived policies despite being relatively easy to spot and correct.