First Person

New York City Charter Lotteries: Hey, You Never Know

A few years ago, the New York State lottery’s slogan was “Hey, you never know.”  In its original formulation, the slogan sought to motivate New Yorkers to play the lottery, a game of chance, on the grounds that you never know unless you play if you are a winner.  But the slogan is a double entendre when applied to Caroline Hoxby’s highly-publicized study of the effects of attending a charter school in New York City.  Propelled by Hoxby’s forceful claims about the superiority of lottery-based research on charter schools, much of the mainstream media has concluded that we now know definitively that New York City charter schools outperform their traditional counterparts—in spite of the fact that her study has not undergone a rigorous peer review process that might identify problems in the study and ways of addressing them.  Today, however, an equally forceful critique prepared by Sean Reardon of Stanford University argues that Hoxby’s research is anything but definitive.  Citing flaws in the statistical analysis of the report, Reardon writes that it “likely overstates the effects of New York City charter schools on students’ cumulative achievement … It may be that New York City’s charter schools do indeed have positive effects on student achievement, but those effects are likely smaller than the report claims.”

Reardon is careful to point out that it’s not possible, based on the information provided in Hoxby’s report and associated documents, to judge the extent of the bias in Hoxby’s estimates of charter school effects on student achievement.  More than anything, he calls for reserving judgment until more information about the study, its data and methods are available, and until the study has undergone rigorous peer review.  Until then, he maintains, it would be unwise to rely on the statistics reported in the study, and the inferences Hoxby and her colleagues draw about charter school effects in New York City.     

Here I’ll mention two of the features of Reardon’s critique that I find particularly persuasive.  The first is that Hoxby used an inappropriate set of statistical models to analyze the data, which likely distorts the charter school effects.  You might be surprised to learn that Hoxby used statistical models at all.  If her results are based on comparing students who won a charter school lottery with students who lost the lottery, and the lottery was fair, balanced and random, why would a model be needed?  It seems like the charter school effect would simply be the difference in the outcomes observed for the lottery winners and the lottery losers.  But comparing lottery winners and losers isn’t really estimating an individual causal effect, because an individual student can’t simultaneously be enrolled in a charter school and a traditional public school.  Even in the context of a lottery, or any other kind of study that can capitalize on a randomization process, such as a clinical drug trial, statistical models come into play to allow for inferences about cause-and-effect relationships.  These inferences are always made in relation to a particular statistical model, and all such models have assumptions.

One of the assumptions that is widely recognized is that a statistical model for causal inference should take account of factors that precede selection into the “treatment”—in this case, enrollment in a charter school versus a traditional public school.  If, hypothetically, charter school attendees were wealthier than traditional public school attendees, we’d want to control for wealth to make the charter and traditional school attendees as comparable as possible.  But it’s just as widely recognized that such a statistical model should not take account of factors that are measured after, and hence potentially influenced by, the treatment.  If attending a charter school increased a student’s motivation, and heightened motivation yields better test scores, then we wouldn’t want to control for motivation in a statistical model for the causal effect of going to charter school on test scores.  That kind of control means that the charter and traditional school attendees are no longer comparable at the time that they began attending a charter versus traditional school, which is the critical time.

Reardon demonstrates that this is precisely what Hoxby and her colleagues do in most of their statistical analyses.  For the analyses of charter school effects on test scores in grades four through eight, she controls for achievement in the prior year—achievement that was observed after the lotteries that determined whether a student enrolled in a charter or traditional public school.  The effects of charter school attendance on test scores in grades four through eight are therefore distorted, but to an unknown degree.  This is not a problem for estimates of the cumulative effect of charter school attendance in grades K-3 on third grade test performance, because the statistical models don’t include prior test scores (as there aren’t any before grade three.)  Reardon therefore finds Hoxby’s estimates of the effect of going to charter school in grades K-3 to be more credible than those for grades four through to eight.  However, the K-3 effect is only one-half to one-third as large as the estimated annual effect of charter school attendance in grades four through eight.    

The second issue is estimation of the cumulative effects of charter school attendance.  Hoxby’s report gets a lot of mileage out of the claim that the effects of attending a charter school from kindergarten to grade eight are large enough to close the performance gap between (predominantly white, upper-class) children in Scarsdale and (predominantly minority, low-income) children in Harlem by 66% in English and 86% in math.  Reardon points out that these figures are based on unrealistic extrapolations.  You can’t simply add up the annual effects of attending a charter school from year to year because the gains decay over time.  Moreover, most of the students in the Hoxby study have been in charter schools for only three or four years;  virtually none have been enrolled in charter schools for as many as nine years, and those would only have been enrolled in the very small number of charter schools that have been open that long, and cannot tell us about the long-term effects of attending the much larger number of newer charter schools.  Reardon’s analysis suggests that Hoxby’s estimate of the cumulative effect of attending a charter school from grades four through eight could be exaggerated by as much as 50%.

Are Caroline Hoxby’s estimates of the effects of attending a charter school rather than a traditional public school in New York City accurate?  Maybe.  But based on Sean Reardon’s critique, probably not.  Hey, you never know.

First Person

I covered Tennessee’s ed beat for Chalkbeat. Here’s what I learned.

PHOTO: Marta W. Aldrich
Grace Tatter covers a press conference at the Tennessee State Capitol in 2015.

For three years, I covered the Statehouse for Chalkbeat Tennessee, reporting on how policies from Nashville trickled down into more than 1,800 public schools across the state.

Now I’m starting back to school myself, pursuing graduate studies aimed at helping me to become a better education journalist. I’m taking with me six things I learned on the job about public education in Tennessee.

1. Apathy is often cited as a major problem facing education. That’s not the case in Tennessee.

I heard from hundreds of parents, educators, and students who were passionate about what’s happening — good and bad — inside of schools. I covered crowded school board meetings and regularly scrambled for an open seat at legislative hearings where parents had filled the room after driving since dawn to beat the opening gavel. Not incidentally, those parents usually came from communities with the “worst” schools and the lowest test scores. While many disagreements exist about the best way to run schools, there is no shortage of people, particularly parents and educators, who care.

2. Tennessee has one of the most fascinating education stories in America.

I’ve had a front-row seat to massive changes in K-12 education under reforms ushered in by Race to the Top — an overhaul being tracked closely well beyond the state’s borders. But the national interest and import doesn’t end with changes stemming from the $500 million federal award. Tennessee is home to some of the nation’s premier education researchers, making its classrooms laboratories for new ideas about pre-K, school turnaround, and literacy instruction, just to name a few. And at the legislature, more lobbyists are devoted to education than to most any other cause. A lot of eyes are on Tennessee schools.

3. The education community is not as divided as it looks.

During the course of just a few years, I watched state lawmakers change their positions on accountability and school vouchers. I witnessed “anti-charter” activists praise charter leaders for their work. I chronicled task force meetings where state leaders who were committed to standardized testing found middle ground with classroom educators concerned that it’s gone too far. In short, a lot of people listened to each other and changed their minds. Watching such consensus-building reminded me that, while there are no simple debates about education, there is a widespread commitment to making it better.

4. Money matters.

Even when stories don’t seem to be about money, they usually are. How much money is being spent on testing, teacher salaries, school discipline reform? How much should be available for wraparound services? Why do some schools have more money than others? Is there enough to go around? Tennessee leaders have steadily upped public education spending, but the state still invests less than most other states, and the disparities among districts are gaping. That’s why more than a handful of school districts are battling with the state in court. Conversations about money are inextricable from conversations about improving schools.

5. Race is a significant education issue, but few leaders are willing to have that conversation.

More than 60 years after Brown v. Board of Education, Tennessee’s schools are largely racially segregated. Yet most policymakers tread lightly, if ever, into conversations about achieving real racial integration. And in many cases — such as a 2011 law enabling mostly white suburban Shelby County towns to secede from the mostly black Memphis district — they’ve actually gone backwards. Then there’s the achievement data. The annual release of test scores unleashes a flurry of conversation around the racial achievement gap. But the other 11 months of the year, I heard little about whether state and local policies are closing those gaps — or contributing to them — or the historical reasons why the gaps exist in the first place. To be sure, state leadership is trying to address some of Tennessee’s shortcomings. For example, the State Department of Education has launched modestly funded initiatives to recruit more teachers of color. But often, race and racism are the elephants in the room.

6. Still, there’s lots to celebrate.

If there were unlimited hours in the day, I could have written thousands of stories about what’s going right in public education. Every day, I received story ideas about collaborations with NASA in Oak Ridge, high school trips to Europe from Memphis, gourmet school lunches in Tullahoma, and learning partnerships with the Nashville Zoo. Even in schools with the steepest challenges, they were stories that inspire happiness and hope. They certainly inspired me.

Grace Tatter graduated from public schools in Winston-Salem, N.C., and received her bachelor’s degree in history from the University of North Carolina. She’s now pursuing a master’s degree in specialized studies at the Harvard Graduate School of Education.

First Person

I’m a Houston geography teacher. This is my plan for our first day back — as soon as it arrives

PHOTO: Creative Commons / Texas Military Department
Texas National Guard soldiers arrive in Houston, Texas to aid citizens in heavily flooded areas from the storms of Hurricane Harvey.

Hurricane Harvey has upended so many things here in Houston, where I am starting my third year as a teacher. One of them is the lesson I am planning for the first day of school — as soon as it arrives.

This upheaval is nothing compared to what people across the city have faced, including my students, who have been sending me photos of evacuation boats going past their houses.

But it is fundamental to the task of being a teacher at a time of crisis. As an A.P. Human Geography teacher, my job is to help students make connections between the geography concepts we are learning in class and their real lives: Does Houston look like the models of urban development we study? Does their family history include a migration?

Before the storm, my thinking went like this: I am white and was born in England and most of my students are Hispanic, many with parents who were born in other countries. I was excited for us to share and compare our different stories. My students last year were shocked and fascinated when they discovered that my white, middle-aged father who is a university professor was applying for a green card, just as many of their family members were.

Now, Hurricane Harvey has underlined for me the importance of those real-world connections. As I looked at the photos from my students, I was struck by how geography concepts can affect us in very real — even life-threatening — ways.

I had planned to teach a lesson at the end of the year about how urbanization affects the environment. The lesson looks at how urbanization can exacerbate flooding: for example, how paving over grassy areas can increase the speed with which rain reaches the bayous, causing the water levels to rise faster. I would then have students evaluate different policies cities can adopt to mitigate that risk, such as encouraging the building on brownfield rather than greenfield sites and passing laws to protect farmland — options that have significant benefits but also significant costs.

I have decided to move this lesson up in the curriculum and teach it when we have school again. School is scheduled to start again on Tuesday, though at this stage everything is provisional, as each hour we find out about more families that have had their homes destroyed by the rising waters. It is still unclear how all our staff, let alone students, will get to school.

I am worried that the lesson could re-traumatize students who have experienced so much trauma in the past few days. I know I will need to make an active effort to make students feel comfortable stepping into the hall if they are feeling overwhelmed. However, my experiences with the recent presidential election make me think that this lesson is exactly what some students might need.

After the election, many students were genuinely confused about what had happened. One question in particular was on their minds: How you can you win the popular vote but not the election? We talked through the Electoral College together, and having clarity about what had happened and why it happened seemed to give them a firmer foundation to build on as they processed their emotions. I am hopeful that teaching about flooding will help ground them in a similar way.

This lesson about flooding was once simply another lesson in the curriculum, but now it has taken on a new urgency. In moments of disaster, it is easy to feel powerless; I certainly could not help the people I saw posting on Facebook that they were been on hold with 911 for hours while standing on their roofs.

Yet teachers have a unique power — the power to shape the minds of future generations to solve the problems that we face. Houston’s location means that it will always be susceptible to flooding. But by teaching about the flood I hope I can play a small role in helping our city avoid repeating some of the tragic scenes I witnessed this week.

Alex McNaughton teaches history and geography at YES Prep Southeast in Houston.

Looking to help? YES Prep is collecting donations to support its students and their families. Houston ISD and KIPP Houston are also soliciting donations for their students.