Drill and Kill Kerfuffle

December 16, 2010

The reaction of New York Times reporter, Sam Dillon, and LA Times reporter, Jason Felch,  to my post on Monday about erroneous claims in their coverage of a new Gates report could not have been more different.  Felch said he would look into the issue, discovered that the claimed negative relationship between test prep and value-added was inaccurate, and is now working on a correction with his editors.

Sam Dillon took a very different tack.  His reaction was to believe that the blog post was “suggesting on the internet that I had misinterpreted an interview, and then you repeated the same thing about the Los Angeles Times. That was just a sloppy and irresponsible error.”  I’m not sure how Dillon jumps to this thin-skinned defensiveness when I clearly said I did not know where the error was made: “I don’t know whether something got lost in the translation between the researchers and Gates education chief, Vicki Phillips, or between her and Sam Dillon at the New York Times, but the article contains a false claim that needs to be corrected before it is used to push changes in education policy and practice.

But more importantly, Dillon failed to check the accuracy of the disputed claim with independent experts.  Instead, he simply reconfirmed the claim with Gates officials: “For your information, I contacted the Gates Foundation after our correspondence and asked them if I had misquoted or in any way misinterpreted either Vicki Phillips, or their report on their research. They said, ‘absolutely not, you got it exactly right.'”

He went on to call my efforts to correct the claim “pathetic, sloppy, and lazy, and by the way an insult.”  I guess Dillon thinks that being a reporter for the New York Times means never having to say you’re sorry — or consult independent experts to resolve a disputed claim.

If Dillon wasn’t going to check with independent experts, I decided that I should — just to make sure that I was right in saying that the claims in the NYT and LAT coverage were unsupported by the findings in the Gates report.

Just to review, here is what Dillon wrote in the New York Times: “One notable early finding, Ms. Phillips said, is that teachers who incessantly drill their students to prepare for standardized tests tend to have lower value-added learning gains than those who simply work their way methodically through the key concepts of literacy and mathematics.”  And here is what Jason Felch wrote in the LA Times: ““But the study found that teachers whose students said they ‘taught to the test’ were, on average, lower performers on value-added measures than their peers, not higher.”  And the correlations in the Gates report between test student reports of test prep and value-added on standardized tests were all positive: “We spend a lot of time in this class practicing for the state test.” (ρ=0.195), “I have learned a lot this year about the state test.” (ρ=0.143), “Getting ready for the state test takes a lot of time in our class.” ( ρ=0.103).  The report does not actually contain items that specifically mention “drill,”work their way methodically through the key concepts of literacy and mathematics,” or “taught to the test,” but I believe the reporters (and perhaps Gates officials) are referencing the test prep items with these phrases.

I sent links to the coverage and the Gates report to a half-dozen leading economists to ask if the claims mentioned above were supported by the findings.  The following reply from Jacob Vigdor, an economist at Duke, was fairly representative of what they said even if it was a bit more direct than most:

I looked carefully at the report and come to the same conclusion as you: these correlations are positive, not negative.  The NYT and LAT reports are both plainly inconsistent with what is written in the report.  A more accurate statement would be along the lines of “test preparation activities appear to be less important determinants of value added than [caring teachers, teacher control in the classroom, etc].”  But even this statement is subject to the caveat that pairwise correlations don’t definitively prove the importance of one factor over another.  Maybe the reporters are describing some other analysis that was not in the report (e.g., regression results that the investigators know about but do not appear in print), but even in that case they aren’t really getting the story right.  Even in that scenario, the best conclusion (given positive pairwise correlations and a hypothetically negative regression coefficient) would be that teachers who possess all these positive characteristics tend to emphasize test preparation as well.

Put another way, it’s alway good to have a caring teacher who is in control of the classroom, makes learning fun, and demands a lot of her students.  Among the teachers who share these characteristics, the best ones (in terms of value added) appear to also emphasize preparation for standardized tets.  I say “appear” because one would need a full-fledged multivariate regression analysis, and not pairwise correlations, to determine this definitively.

Another leading economist, who preferred not to be named, wrote: “I looked back over the report and I think you are absolutely right!”  I’m working on getting permission to quote others, but you get the idea.

In addition to confirming that a positive correlation for test prep items means that it contributes to value-added, not detracts from it, several of these leading economists emphasized the inappropriateness of comparing correlations to draw conclusions about whether test prep contributes to value-added any more or less than other teacher practices observed by students.  They noted that any such comparison would require a multivariate analysis and not just a series of pairwise correlations.  And they also noted that any causal claim about the relative effectiveness of test prep would require some effort to address the endogeneity of which teachers engage in more test prep.

As David Figlio, an economist at Northwestern University, put it:

You’re certainly correct here.  A positive pairwise correlation means that these behaviors are associated with higher performance on standardized tests, not lower performance.  The only way that it could be an accurate statement that test prep is causing worse outcomes would be if there was a negative coefficient on test prep in a head-to-head competition in a regression model — though even then, one would have to worry about endogeneity: maybe teachers with worse-performing students focus more on test prep, or maybe lower-performing students perceive test prep to be more oppressive (of course, this could go the other way as well.)  But that was not the purpose or intent of the report.  The report does not present this as a head-to-head comparison, but rather to take a first look at the correlates between practice measures and classroom performance.

There was no reason for this issue to have developed into the controversy that it has. The coverage contains obvious errors that should have been corrected quickly and clearly, just as Jason Felch is doing.   Tom Kane, Vicki Phillips, and other folks at Gates should have immediately issued a clarification as soon as they were alerted to the error, which was on Monday.

And while I did not know where the error occurred when I wrote the blog post on Monday, the indications now are that there was a miscommunication between the technical people who wrote the report and non-technical folks at Gates, like Vicki Phillips and the pr staff.  In other words, Sam Dillon can relax since the mistake appears to have originated within Gates (although Dillon’s subsequent defensiveness, name-calling, and failure to check with independent experts hardly bring credit to the profession of journalism).

The sooner Gates issues a public correction, the sooner we can move beyond this dispute over what is actually a sidebar in their report and focus instead on the enormously interesting project on which they’ve embarked to improve measures of teacher effectiveness.  An apology from Sam Dillon would be also nice but I’m not holding my breath.


School Choice Reduces Crime, Increases College-Attendance, and Makes Your Breath Smell Better

November 29, 2009

Well, at least the first two claims are supported by rigorous new research based on school choice lotteries in Charlotte, North Carolina. Harvard researcher, David Deming, looked at a public school choice program that allows families to rank order their preferred schools and then admits students by a weighted lottery formula.  The program is designed primarily to facilitate school integration but it also allows random-assignment designed research of the effects of choice.  In the paper, “Better Schools, Less Crime?” , Deming found: 

Seven years after random assignment, lottery winners have been arrested for fewer and less serious crimes, and have spent fewer days incarcerated…  The reduction in crime persists through the end of the sample period, several years after enrollment in the preferred school is complete. The effects are concentrated among African-American males whose ex ante characteristics define them as “high risk.”

In another paper Deming wrote with Justine Hastings, Tom Kane and Doug Staiger, they examined the same Charlotte program but this time focused on the effects of choice on high school completion and college attendance.  They found:

We find strong evidence that high school lottery winners from neighborhoods assigned to the lowest-performing schools benefited greatly from choice. Girls are 12 percentage points more likely to attend a four-year college. Boys are 13 percentage points more likely to graduate from high school but are less likely to attend a four-year college. We present suggestive evidence that changes in relative rank within schools may explain these puzzling gender differences. In contrast with the results for students from low-performing home school zones, we find little evidence of gains for students whose home schools are of average quality.

So, expanding school choice reduces the likelihood that students will become criminals (particularly among African-American males) and increases the chances that boys will graduate high school and girls will attend college.  Given previous research showing that choice increases achievement for participating students, students who remain in traditional public schools, and improves civic goals (like school integration) in addition to these new findings, maybe choice really does make your breath smell better.  It seems to do so many other useful things.

The Growing Charter School Consensus

January 15, 2009

A string of high quality studies is finding that students benefit academically from attending a charter school rather than a traditional public school. 

First we had a random-assignment study of Chicago charter schools by Caroline Hoxby and Jonah Rockoff that found “that students in charter schools outperformed a comparable group of lotteried-out students who remained in regular Chicago public schools by 5 to 6 percentile points in math and about 5 percentile points in reading.” 

Then Hoxby conducted a random-assignment study of charter schools in New York City and found: “that the average effect of the charter schools on math is 0.09 standard deviations for every year that a student spends in his or her charter school. The average effect on reading is 0.04 standard deviations for every year that a student spends in his or her charter school.” 

Then Kevin Booker (Mathematica), Tim Sass (Florida State), Brian Gill (Mathematica), and Ron Zimmer (Rand)used a well-designed instrumental variable analysis to see whether charter middle-schoolers who continue to charter high schools are more likely to graduate.  They are. 

And most recently a random-assignment analysis of charter schools in Massachusetts led by Tom Kane at Harvard and Josh Angrist at MIT found that charter school students accepted by lotteries significantly outperformed their counterparts in traditional public schools, unless the charter school was operated by the teacher unions.

In light of these high quality studies, it is harder to oppose charter schools on a scholarly basis.  And with the clear support of charters from the incoming Obama administration, it is getting harder to opposed charter schools on a political basis — at least at the national level.

But don’t expect to see the teacher unions waving a white flag despite their losses in research and national politics.  They don’t need facts or the support of the US Department of Education so long as they continue to dominate local school politics. 

And that is exactly why they have focused on organizing local charter schools to neutralize the threat to their grip on local school politics.  As my colleague Marcus Winters writes today in the New York Post, the unions managed to organize two successful charter schools in New York City.  The fact that union-run charter schools in Massachusetts trailed the non-union charters in performance is not of concern to the unions.  It isn’t about student achievement; it’s about keeping their hold on power even as the facts pile up against them.