Tag Archives: education

No, early marriage is not more common for college graduates

Update: IFS has taken down the report I critiqued here, and put up a revised report. They have added an editor’s note, which doesn’t mention me or link to this post:

Editor’s Note: This post is an update of a post published on March 14, 2018. The original post looked at marriage trends by education among all adults under age 25. It gave the misimpression that college graduates were more likely to be married young nowadays, compared to non-college graduates.

At the Institute for Family Studies, Director of Research Wendy Wang has a post up with the provocative title, “Early Marriage is Now More Common For College Graduates” (linking to the Internet Archive version).

She opens with this:

Getting married at a young age used to be more common among adults who didn’t go to college. But the pattern has reversed in the past decade or so. In 2016, 9.4% of college graduates ages 18 to 24 have ever been married, which is higher than the share among their peers without a college degree (7.9%), according to my analysis of the most recent Census data.

And then the dramatic conclusion:

“What this finding shows is that even at a young age, college-educated adults today are more likely than their peers without a college degree to be married. And this is new.”

That would be new, and surprising, if it were true, but it’s not.

Here’s the figure that supports the conclusion:


It shows that 9.4% of college graduates in the age range 18-24 have been married, compared with 7.9% of those who did not graduate from college. (The drop has been faster for non-graduates, but I’m setting aside the time trend for now.) Honestly, I guess you could say, based on this, that young college graduates are more likely than non-graduates to “be married,” but not really.

The problem is there are very very few college graduates in the ages 18-19. The American Community Survey, which they used here, reports only about 12,000 in the whole country, compared with 8.7 million people without college degrees ages 18-19 (this is based on the public use files that IPUMS.org uses; which is what I use in the analysis below). Wow! There are lots and lots of non-college graduates below age 20 (including almost everyone who will one day be a college graduate!), and very few of them are married. So it looks like the marriage rate is low for the group 18-24 overall. Here is the breakdown by age and marital status for the two groups: less than BA education, and BA or higher education — on the same population scale, to help illustrate the point:


If you pool all the years together, you get a higher marriage rate for the college graduates, mostly because there are so few college graduates in the younger ages when hardly anyone is married.

To show the whole thing in terms of marriage rates, here is the marital status for the two groups at every age from 15 (when ACS starts asking about marital status) to 54.


Ignoring 19-21, where there are a tiny number of college graduates, you see a much more sensible pattern: college graduates delay marriage longer, but then have higher rates at older ages (starting at age 28), for all the reasons we know marriage is ultimately more common among college graduates. In fact, if you used ages 15-24 (why not?), you get an even bigger difference — with 9.4% of college graduates married and just 5.7% of non-college graduates. Why not? In fact, what about ages 0-24? It would make almost as much sense.

Another way to do this is just to look at 24-year-olds. Since we’re talking about the ever-married status, and mortality is low at these ages, this is a case where the history is implied in the cross-sectional data. At age 24, as the figure shows, 19.9% of non-college graduates have been married, compared with 12.9% of college graduates. Early marriage is not more common for college graduates.

In general, I don’t recommend comparing college graduates and non-graduates, at least in cross-sectional data, below age 25. Lots of people finishing college below age 25 (and increasingly after that age as well). There is also an important issue of endogeneity here, which always makes education and age analysis tricky. Some people (mostly women) don’t finish college because they get married and have children).

Anyway, it looks to me like someone working for a pro-marriage organization saw what seemed like a story implying marriage is good (that’s why college graduates do it, after all), and one that also fits with the do-what-I-say-not-what-I-do criticism of liberals, who are supposedly not promoting marriage among poor people while they themselves love to get married (a critique made by Charles Murray, Brad Wilcox, and others). And, before thinking it through, they published it.

Mistakes happen. Fortunately, I dislike the Institute for Family Studies (see the whole series under this tag), and so I read it and pointed out this problem within a couple hours (first on Twitter, less than two hours after Wang tweeted it). It’s a social media post-publication peer review success story! If they correct it.


Filed under Research reports

Black women really do have high college enrollment rates (at age 25+)

The other day I reported on the completely incorrect meme that Black women are the “most educated group” in the U.S. That was a simple misreading of a percentage term on an old table of degree attainment, which was picked up by dozens of news-repeater websites. Too many writers/copiers and editors/selectors don’t know how to read or interpret social statistics, so this kind of thing happens when the story is just too good to pass up.

I ignored another part of those stories, which was the claim that Black women have the highest college enrollment rates, too. This is more complicated, and the repeated misrepresentation is more understandable.

Asha Parker in Salon wrote:

By both race and gender there is a higher percentage of black women (9.7 percent) enrolled in college than any other group including Asian women (8.7 percent), white women (7.1 percent) and white men (6.1 percent), according to the 2011 U.S. Census Bureau.

You know the rewrite journalists are playing telephone when they all cite the same out-of-date statistics. (That Census report comes out every year — here’s the 2014 version; pro-tip: with government reports, try changing the year in the URL as a shortcut to the latest version.)

But is that true? Sort of. Here I have to blame the Census Bureau a little, because on that table they do show those numbers, but what they don’t say is that 9.7% (in the case of Black women) is the percentage of all Black “women” age 3 or older who are attending college. On that same table you can see that about 2% of Black “women” are attending nursery school or kindergarten; more relevant, probably, is the attendance rate for those ages 3-4, which is 59%.

So it’s sort of true. Particularly odd on that table is the low overall college attendance rate of Asian women, who are far and away the most likely to go to college at the “traditional” college ages of 18-24. That’s because they are disproportionately over age 25 (partly because many have immigrated as adults). But, if you just limit the population to those ages 18-54, Black women still have the highest enrollment rates: 15.5%, compared with 14.6% for Asians, 12.6% for Hispanics, and 12.4% for Whites. Asians are just the most likely to be over 25 and not attending college, most of them having graduated college already.

This does not diminish the importance of high enrollment rates for Black women, which are real — after age 25; the pattern is interesting and important. Here it is:


Under age 25, Black women are the least likely to be in college, over 25 they’re the most likely. This really may say something about Black women’s resilience and determination, but it is not a feel-good story of barriers overcome and opportunity achieved. And, despite her presence in the videos and stories illustrating this meme, it is not the story of Michelle Obama, who had a law degree from Harvard at age 24.

This is part of a pattern in which family events are arrayed differently across the life course for different race/ethnic groups, and the White standard is often mistaken as universal. I have noted this before with regard to marriage (with more Black women marrying at later ages) and infant mortality (which Black women facing the lowest risk of infant death when they have children young). It’s worth looking at more systematically.

ADDENDUM 6/29/2016: Cumulative projected years of higher education

If you take the proportion of women enrolled in each age group, multiply it by the years if the age group (so, for example, 18-19 is two years), and sum up those products, you can get a projected total years in college (including graduate school) for each group of women. It looks like this:


Note this makes the unreasonable assumption that everyone who says they are enrolled in college in an October survey attends college for a full year. So, for example, Asian women are projected to spend 6.2 years in college on average between ages 18 and 54. What’s interesting here is that Black women are projected to spend more years in higher education than White women (5.5 versus 4.9). But we know they are much less likely than White women to end up with a bachelor’s degree (currently 23% versus 33%). This has to be some combination of Black women not spending full years in college, not going to school full time, or not completing bachelor’s degrees after however many years in school. Attendance may be an indicator of resilience or determination, but it’s not as good an indicator of success.


Filed under In the news

No Black women are not the “most educated” group in the US

I don’t know where this started, but it doesn’t seem to be stopping. The following headlines are all completely factually wrong, and the organizations that published them should correct them right away:

The Root: Black Women Now the Most Educated Group in US

Upworthy: Black women are now America’s most educated group

SalonBlack women are now the most educated group in the United States

GoodBlack Women Are Now The Most Educated Group In The U.S.

And then the video, by ATTN:, on Facebook, with 6 million views so far. I won’t embed the video here, but it includes these images, with completely wrong facts:



What’s true is that Black women, in the 2009-2010 academic year, received a higher percentage of degrees within their race/ethnic group than did women in any other major group. So, for example, of all the MA degrees awarded to Black students, Black women got 71% of them. In comparison, White women only got 62% of all White MA degrees. Here is the chart, from the data that everyone linked to (which is not new data, by the way, and has nothing to do with 2015):


For Black women to be the “most educated group,” they would have to have more degrees per person than other groups. In fact, although a greater percentage of Black women have degrees than Black men do, they have less education on average than White women, White men, Asian/Pacific Islander women, and Asian/Pacific Islander men.

Here are the percentages of each group that holds a BA degree or higher (ages 25-54), according to the 2010-2014 American Community Survey, with Black women highlighted:


23% of Black women ages 25-54 have BA degrees or more education, compared with 38% of White women. This does not mean Black women are worse (or that White women are better). It’s just the actual fact. Here are the percentages for PhD degrees:


Just over half of 1% of Black women have PhDs, compared with just over 1% of White women – and almost 3% of Asian/PI women. White women are almost twice as likely to have a PhD and Black women, Asian/PI women are more than 5-times as likely.

Racism is racism, inequality is inequality, facts are facts. Saying this doesn’t make me racist or not racist, and it doesn’t change the situation of Black women, who are absolutely undervalued in America in all kinds of ways (and one of those ways is that they don’t have the same educational opportunities as other groups). There are some facts in these stories that are true, too. And of course, why Black women (and women in general) are getting more degrees than men are is an important question. But please don’t think it’s my responsibility to research and present all this information correctly before it’s appropriate for me to point out the obvious inaccuracy here. You don’t need this meme to do the good you’re trying to do by sharing these stories.

Our current information economy rewards speed and clickability. Journalists who know what they’re doing are more expensive and slower. Making good graphics and funny GIFs is a good skill, but it’s a different skill than interpreting and presenting information. We can each help a little by pausing before we share. And those of us with the skills and training to track these things down should all pitch in and do some debunking once in a while. For academics, there is little extra reward in this (as evidenced by my most recent, sup-par departmental “merit” review), beyond the rewards we already get for our cushy jobs, but it should be part of our mission.


Filed under In the news

Sex ratios as if not everyone is a college graduate

Quick: What percentage of 22-to-29-year-old, never-married Americans are college graduates? Not sure? Just look around at your friends and colleagues.

Actually, unlike among your friends and colleagues, the figure is only 27.5% (as of 2010). Yep, barely more than a quarter of singles in their 20s have finished college. Or, as the headlines for the last few days would have it: basically everyone.

The tweeted version of this Washington Post Wonkblog story was, “Why dating in America is completely unfair,” and the figure was titled “Best U.S. cities for dating” (subtitle: “based on college graduates ages 22-29”). This local news version listed “best U.S. cities for dating,” but never even said they were talking about college graduates only. The empirical point is simple: there are more women than men among young college graduates, so those women have a small pool to choose from, so we presume it’s hard for them to date.* (Also, in these stories everyone is straight.) In his Washington Post excerpt the author behind this, Jon Birger, talks all about college women. The headline is, “Hookup culture isn’t the real problem facing singles today. It’s math.” You have to get to the sixth paragraph before you find out that singles means college and post-college women.

In his Post interview the subject of less educated people did come up briefly — if they’re men:

Q: Some of these descriptions make it sound like the social progress and education that women have obtained has been a lose-lose situation: In the past women weren’t able to get college educations, today they can, but now they’re losing in this other realm [dating]. Is it implying that less educated men are still winning – they don’t go to college but they still get the pick of all these educated, more promiscuous women?

A: Actually, it’s the opposite. Less educated men are actually facing as challenging a dating and marriage market as the educated women. So for example, among non-college educated men in the U.S. age 22 to 29, there are 9.4 million single men versus 7.1 million single women. So the lesser-educated men face an extremely challenging data market. They do not have it easy at all.

It’s almost as if the non-college-educated woman is inconceivable. She’s certainly invisible. The people having trouble finding dates are college-educated women and non-college-educated men. By this simple sex-ratio logic, it should be raining men for the non-college women. Too bad no one thought to think of them.

Yes, the education-specific sex ratio is much better for women who haven’t been to college. That is, they are outnumbered by non-college men. But it’s not working out that well for them in mating-market terms.

I can’t show dating patterns with Census data (and neither can Birger), but I can show first-marriage rates — that is, the rate at which never-married people get married. Here are the education-specific sex ratios, and first-marriage rates, for 18-34-year-old never-married women in 279 metropolitan areas, from the 2009-2011 American Community Survey.** Blue circles for women with high school education or less, orange for BA-holders (click to enlarge):


Note that for both groups marriage rates are lower for women when there are more of them relative to men — the downward sloping lines (which are weighted by population size). Fewer men for women to choose from, plus men eschew marriage when they’re surrounded by desperate women, so lower marriage rates for women. But wait: the sex ratios are so much better for non-college women — they are outnumbered by male peers in almost every market, and usually by a lot. Yet their marriage rates are still much lower than the college graduates’. Who cares?

I don’t have time to get into the reasons for this pattern; this post is media commentary more than social analysis. But let’s just agree to remember that non-college-educated women exist, and acknowledge that the marriage market is even more unfair for them. Imagine that.***

* I once argued that this could help explain why gender segregation has dropped so much faster for college graduates.

** It was 296 metro areas but I dropped the extreme ones: over 70% female and marriage rates over 0.3.

*** Remember, if we want to use marriage to solver poverty for poor single mothers, we have enough rich single men to go around, as I showed.

A little code:

I generated the figure using Stata. I got the data through a series of clunky Windows steps that aren’t easily shared, but here at least is the code for making a graph with two sets of weighted circles, each with its own weighted linear fit line, in case it helps you:

twoway (scatter Y1 X1 [w=count1], mc(none) mlc(blue) mlwidth(vthin)) ///

(scatter Y2 X2 [w=count2], mc(none) mlc(orange_red) mlwidth(vthin)) ///

(lfit Y1 X1 [w=count1], lc(blue)) ///

(lfit Y2 X2 [w=count2], lc(orange_red)) , ///

xlabel(30(10)70) ylabel(0(.1).3)


Filed under In the news

Social class divides the futures of high school students

There is new research from the National Center for Education Statistics (NCES), written up by Susan Dynarsky at the New York Times Upshot. The striking finding is that poor children in the top quartile on high school math scores have a 41% chance of finishing a BA degree by their late twenties — the same chance as children from the second-lowest quartile in math scores who are high-socioeconomic status (SES). Poor children from the third-highest quartile in high school math have graduation about equal to the worst-scoring children form the richest group. Here’s the figure:


The headline on the figure is misleading, actually, since SES is not measured by wealth, but by a combination of parental education, occupation, and income. (Low here means the bottom quartile of SES, Middle is the 25th to 75th percentile, and High is 75th and up.)

One possible mechanism for the disparity in college completion rates is education expectations. Dynarsky mentions expectations measured in the sophomore year of high school, which was 2002 for this cohort. What she doesn’t mention is how much those expectations changed by senior year. Going to the NCES source for that data (here) I found this chart, which I annotated in red:


Between sophomore and senior year, the percentage expecting to finish a BA degree or more decreased and the percentage expecting to go to two-year college increased, across SES levels. But the change was much greater for lower SES students. So the gap in expecting to go to two-year college between high- and low-SES students grew from 6 to 17 percentage points; that is, from 9% versus 3% in the sophomore year to 22% versus 6% in the senior year. That’s a big crushing of expectations that happened in the formative years at the end of high school.


Filed under Research reports

Why are women with advanced degrees having more children?

There are a few puzzles in the latest news on U.S. fertility trends.


The issues behind fertility trends and patterns are complex, reflecting changing social and well as biological influences, and demanding careful attention to methods. Birth rates can be measured as annual events (such as the percentage of women having a birth in a given year) or as life-course outcomes (such as the percentage of women who reach age 45 without ever having a birth). Comparisons over time are confounded by changes in the composition of the population with regard to age, and some subgroups are subject to changing composition as a result of social or cultural, rather than biological, trends. For example, consider that a woman may spend the years from age 22 to age 43 as a college graduate, and then register an advanced degree at age 44. That means her births in the previous 20 years count among those with BAs, while her “completed fertility” would be counted among those with advanced degrees.

The news

It’s been a confusing few days for fertility-news watchers, so I’ll try to muddle it up a little more. I ran some numbers for a conversation I had with New York Times Upshot reporter Claire Cain Miller, which she reported under the title, “Births to Single Mothers Are Down, Except for Those 35 and Older.” I’ll show those here. They go along with the various headlines about Gretchen Livingston’s new Pew report, “Childlessness Falls, Family Size Grows Among Highly Educated Women,” reported by Brigid Schulte as, “Why educated women are having more babies.”

Here’s Miller’s chart, based on federal registered birth data. Note these are birth rates for women who aren’t married, which is not the same as the percentage of births occurring to women who aren’t married:


For unmarried women of all ages except 15-17, birth rates increased from 2002 to 2007. As I’ve shown before for women overall, the trend shows the increasing delay of childbearing, with a steeper rise for women ages 30-34 than for those in their early 20s. After 2007, however, reflecting the recession, birth rates fell for all unmarried women except those ages 35 and up. The conventional explanation for this has been that individuals and couples delayed births when they were financially squeezed, but those running up against the end of their fertile years couldn’t delay without risking infertility.

To see how this is working for single women in particular (and single here includes those who are cohabiting), it’s helpful to break it down by age and education. Older women face the biological clock issue regardless of their education level, and women with less education had greater exposure to recession-related hardship. What I showed Miller was this chart, which I made from American Community Survey (ACS) data provided by IPUMS.org. The solid lines are all unmarried women ages 15-44 — red for less than BA, blue for BA plus — while the dotted lines are just the older subgroup, 35-44. This shows that the volatility is greatest for women without BAs. And there is no real recession decline for the 35+ groups:

unmarried births ACS 01-13.xlsx

Based on that, Miller wrote:

During the recession, the decline in single motherhood was entirely attributable to women without college degrees, according to census data analyzed by Philip Cohen, a sociologist at University of Maryland who writes a blog called Family Inequality.

These are “women for whom the hardships of single motherhood are most acute,” Mr. Cohen said. “This could be deliberate planning, or it could reflect relationship problems or economic stress undermining their family plans.”

Among older women who are unmarried, ages 35 to 39, however, the birthrate was 48 percent higher in 2012 than in 2002, according to the National Center for Health Statistics. The increase was driven by college-educated women, according to Mr. Cohen’s analysis. “The delay in general fits a long-term pattern: that family formation is increasingly delayed until women are more established, spend more time in education and more time developing their careers,” he said.

This is tricky because of course single women without BAs do have higher birth rates, so it’s not like poor women just can’t afford to have children — but as a group they were affected more by the crisis. What that means is that a greater proportion of them were affected in such a way as to reduce their fertility than among other groups.

Falling childfreeness

Although it seems contradictory on the surface, this is consistent with Livingston’s headline: Childlessness Falls, Family Size Grows Among Highly Educated Women. Although my figure only shows single women, look at the BA-holding 35+ women: their birth rates rose about 50% from the beginning of the decade till the recession, from about 10 per 1000 to about 15 per 1000, a rate they held through the recession.

But Livingston’s data are “completed” cohort fertility — estimated by the number of children women have had when they’re surveyed in the ages 40-44. Here’s her rather shocking chart:


My chart was annual birth rates. But hers is more interesting because it captures the life course more. What is it that is making women with advanced degrees have bigger families — and making fewer of them have no children at all?

There are several tricky things here, which I’ll show with data in a minute. They are:

  • The advanced-degree group has grown less select as it has grown — more women are entering this category. In particular, there are more Black and Hispanic women going beyond BAs, as well as presumably more women from poor backgrounds. So that might increase the birthrates of the group.
  • On the other hand, although marriage is more common among women with more education — and growing increasingly so — the proportion married among women going for advanced degrees has still fallen. Since married women have more children, this should lower fertility of higher-education women. (A quick check shows a slight decline in the proportion married among advanced degree holders under age 45 from 1990 to 2013, from 68% to 66%.)
  • Finally, as more women get BA degrees and go straight into additional schooling, the average age of women getting advanced degrees has fallen. That gives them more time to rack up births before hitting 44. (To make matters impossibly complicated, if they hold off on having children till they finish their advanced degrees, they will probably be younger when they graduate, as some graduate students with children might tell you.)

Remember that people make decisions about childbearing and education at the same time. If more women decide to get advanced degrees with the goal of having more children from a position of strength, then the statistics will show more women with advanced degrees having children — even if the decisions weren’t made in the order we assume.

It’s hard to get at this with the data we have. The population data we have on education and family characteristics doesn’t tell you when people got their degrees, which means those late 44-year-old medical school graduates are hard to pin down. Ideally, then, we’d have a measure of who is attending school, which would tell us who is on the way toward a degree. But the data from the Current Population Survey that Livingston used didn’t have measure of school attendance for people over age 25 until 2013. So I used the 1990 decennial Census and the 2013 ACS, which both have a measure of school attendance. Unfortunately, the 1990 Census doesn’t identify births, so I counted women as having had a birth if they were living in their own (or their husbands’) households with an “own child” age 0, which is not bad.

I took all the women ages 20-44 who already had a BA degree or higher, were attending school, and were living in their own (or their husbands’) households. In 1990 this was 3.4% of all women in that age group, and by 2013 it was 4.7% — a much bigger group. In 1990 3.5% of them had an infant, but that had increased to 4.6% by 2013. This is consistent with the Livingston finding that they are going to get advanced degrees and reach age 40-44 with more kids (if they experienced this birth rate difference every year, the completed fertility rates would be much higher for the later cohort).

Here are the breakdowns of the two cohorts according to the risk factors for childbearing I just described:

BAs attending school.xlsx

Notice: There are more in their prime childbearing ages (25-34), fewer married, and more Black and Hispanic. As it turns out, a regression analysis shows that the age change accounts for about a quarter of the increase in childbearing, while the change in marital status goes the other way about 8%, meaning they would have had even more kids if more were married. The race/ethnic effects are very small.

That also means the increase in fertility is not just compositional, the result of demographic changes. There is still an increasing tendency to have a child in this group, holding constant these factors. Adjusting for marital status and race/ethnicity, here are the predicted probabilities of having a birth in 1990 and 2013, by age:


Although the younger average age is a big factor, then, there is also a higher chance of having a birth at every age for college graduates pursuing advanced degrees. Why?


The optimistic interpretation of rising fertility for women with advanced degrees is that the cultural and organizational context has changed the childbearing calculus. The husbands or partners of these women are more supportive now. And their workplaces — or the workplaces they anticipate entering — have grown more accepting of professional women with children. Some schools have childcare and lactation spaces for graduate students. So having children may seem more reasonable. It’s also possible — and this is not contradictory — that the growth of this group has been driven by those who are less narrowly focused on their careers. To be a woman pursuing an advanced degree in 1990 you had to be a little more of a pioneer than you do now, so that path may have attracted a different group of women.

On the other hand, this is consistent with an inequality story: that those with better jobs and economic security, and family stability, have a growing advantage when it comes to raising children. Looking forward, I worry that the logistics of successful parenting are becoming an insurmountable challenge for too many people who don’t have enough control over their work lives. If we don’t improve the situation with healthcare, childcare, and family leave, then we risk increasingly making children a luxury that fewer families believe they can afford.

We are trying to fit our rapidly evolving social lives within the relatively narrow biological limits of human reproduction. The inconvenient truth is that the biological prime years for reproduction are also essential years for developing our human capital and adult relationships. We need collective efforts in the form of social policy to manage this compression.


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Charter, private, and wealthy schools lead California vaccine exemptions

We need to know who’s driving this epidemic of non-vaccination so we can decide what to do about it. One key element of the pattern is that it’s a practice of groups, not (just) individuals. And one way such groups are organized and maintained may be by interacting in and around schools — hotspots for parenting fads and identity performance, as well as (one hopes) useful information.

Kieran Healy the other day posted some visualizations of California vaccine exemption rates across schools and counties — then dug deeper on school type here. While he was writing his second post I followed his links to the data and did some more descriptive work, adding some more information on school type and now poverty levels.

I used this California Department of Education data source for the free-lunch eligibility rates (2013-2014), and this California Department of Public Health data source for the vaccine exemption rates for kindergartners (2014-2015). The measure of vaccine exemption is the “Personal Belief Exemption (PBE), whereby a parent requests exemption from the immunization requirements for school entry.” Some of them got supposedly got counseling before making the request, while others further requested a religious exemption from the counseling — those two groups are combined here in the PBE rate. I weighted the analyses by the number of kindergartners enrolled in each school, so the rates shown are for students, not schools (this also helps with the outliers, which are mostly very small schools).

1. Runaway vaccine exemptions are problems of the private and charter schools

I don’t know what percentage of kids need to be immunized, for which diseases, for the proper level of community protection. But these distributions are very skewed, so it makes sense to look at the extremes. Here are three measures, for just under 7,000 schools: the mean percent PBE (the average percent exempt among each kids’ classmates), the percentage of kids in a school with no exempt kindergartners, and the percentage of kids attending schools with more than 5% exempt.


The average charter school kindergartner goes to school with classmates almost 5-times more likely to be non-vaccinated; and charter school kids are more than 3-times as likely to be in class with 5% or more kids exempt.

2. Schools with lots of poor kids have much lower exemption rates

The relationship between exemption rates and percentage of children eligible for free lunch is negative and very strong. Because there are so many schools with no PBEs, I used a tobit regression to predict exemption rates (I also excluded the top 1% outliers). Note the private schools are excluded here because the free lunch data was missing for them. Here is the output:


Just in case the zeros are data errors, I reran the regression excluding the zero cases (logged and not logged), and got weaker but still very strong results.

I illustrate the relationship in the next section.

3. The poverty-exemption relationship is stronger in charter schools

Charter schools have fewer kids eligible for free-lunch than regular public schools (43% versus 55%). However, although the relationship between poverty and exemptions is strong in both charter and regular public schools, it is stronger in the charter schools (the interaction term is almost 7-times its standard error). Here they are, showing the steeper free-lunch slope for charter schools (with a logged y-axis):


Rich charter schools on average have the highest exemption rates, while poor schools — charter or not — are heavily clustered around zero (note it’s jittered so you can see how many cases are at zero).

Update: Here is the same data, for all public schools, presented more simply:


One interpretation of this pattern goes like this: Charter schools do not per se promote vaccine exemption. But because they are more parent-driven, or targeted at certain types of parents, charter schools are more ideologically homogeneous. And because anti-vaccine ideology is concentrated among richer parents, charter schools provide them with a fertile breeding ground in which to generate and transmit anti-vaccine ideas. That’s why, although richer parents in general are driving vaccine denial, it’s especially concentrated in charter schools. This seems consistent with the general echo-chamber nature of information sharing in cultural niches, and the clusering/contagious nature of parenting fads. (The same may or may not hold for private schools.) This could be totally wrong — I’m open to other interpretations.

I’m also happy to share my data on request, but I’m not posting it yet because when I tinker with it more I might make corrections.


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