Gender Gaps in College STEM Education: Boys Tend to be Over-Confident in Math and Benefit from It

February 15, 2018

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(Guest Post by Gema Zamarro & Lina M. Anaya)

Employment in the so-called STEM (Science, Technology, Engineering and Mathematics) fields is projected to continue growing according to the Bureau of Labor Statistics. Additionally, wages in STEM field occupations are estimated to be on average nearly double the national average of wages for non-STEM jobs. Despite this promising future, women continue to be under-represented in STEM. Women are less likely to enroll in STEM degrees in college and represent a smaller share of STEM occupations. The question is why? Only after understanding the possible sources of such gender gaps we can have an idea of what can be done about it.

This question has haunted me (Gema) since my daughter, then a kindergartener, came home one day saying a boy in her class told her “girls are not good in math.”  Indeed, researchers have pointed out at gender differences in math performance and math perceived ability as possible drivers of later gender gaps in STEM. I wondered if parents could somehow counter these effects. After all, my previous work indicated that parental occupation type could be important for women’s long term STEM outcomes. In a recent working paper, I partnered with Lina M. Anaya, a Ph.D. student at the Department of Education Reform at the University of Arkansas, and Frank Stafford, Economics professor at the University of Michigan, to try and shed some light on these questions, using data from the Panel Study of Income Dynamics (PSID).

Using information from the multiple supplements of the PSID, we measured gender gaps in performance  on the standardized Woodcock  Johnson Applied problems test (W-J AP) and self-reported perceived math ability, measured on children from PSID families when they were between 6 and 17 years old (on average around 11 years old). Then, we are able to track these children and study their likelihood of majoring in a STEM field in college. We found that boys are more confident in their abilities than is warranted by their performance, while girls are less confident than is warranted by their performance.  But the problem isn’t just one of lack of confidence — boys’ confidence contributes more to their pursuit of STEM majors than girls’ confidence, even if they had the same true ability and same level of confidence.

Our results corroborated significant gender differences in W-J AP test performance and in perceived math ability during childhood. Even after conditioning in a given level of math performance in the W-J AP test, girls reported significantly lower levels of perceived math ability than boys (See Table 1). In the highest percentiles of math performance, 64% of boys reported the highest levels of perceived math ability, as compared to 50% of the girls. Even in the lowest levels of math performance, boys tended to be more optimistic with respect to their math ability, 29% of the boys reported the highest levels of perceived math ability, relative to 17% of the girls doing so. Having a parent with an occupation in STEM helped increase math performance but did not seem to help improve perceived math ability, if anything it seemed that those with parents in science were more pessimistic.

Table 1: Perceived Math Ability by Gender, given W-J AP scores (% of sample)

    Perceived Math Ability
W-J AP (percentile) Gender 1 to 3 4 to 5 6 to 7
0-50 Boys 15.9% 55.1% 29.0%
Girls 18.7% 64.2% 17.1%
51-80 Boys 4.1% 44.3% 51.6%
Girls 6.5% 49.9% 43.6%
81-100 Boys 2.8% 32.7% 64.4%
Girls 4.6% 45.2% 50.2%

Note: Weighted percentages reported using child population weights

Interestingly, girls’ lack of perceived ability seems to be something specific to math and not the result of girls generally reporting lower levels of perceived ability. The PSID also included results in the Woodcock Johnson reading test (W-J reading) and asked kids to report on their perceived ability in reading. We use this information to study perceived ability in reading conditional on performance. As it can be seen in the results in Table 2, gender patterns are very different for reading, a subject where girls, on average, outperform boys. In this case, we observe smaller gender differences of perceived reading ability among those scoring in the higher percentiles of the W-J reading test while girls performing in the lower percentiles report higher levels of perceived ability than boys.

Table 2: Perceived Reading Ability by Gender, given W-J reading scores (% of sample)

    Perceived Reading Ability
W-J Reading (percentile) Gender 1 to 3 4 to 5 6 to 7
0-50 Boys 13.4% 57.8% 28.8%
Girls 9.2% 50.1% 40.7%
51-80 Boys 4.3% 47.1% 48.6%
Girls 3.4% 32.4% 64.1%
81-100 Boys 1.9% 29.5% 68.6%
Girls 1.5% 33.5% 65.0%

Note: Weighted percentages reported using child population weights

Finally, since the PSID tracked these kids, we study to what extent math performance and perceived math ability, during childhood, and parental occupation type are related to the probability of majoring in STEM during college. Overall, as expected, we find that women are less likely to major in STEM in our sample, especially when we look at the so called “hard sciences” fields of engineering, architecture, mathematics and computer sciences. Both higher levels of math performance in the W-J AP test and higher levels of perceived math ability are related to higher probabilities of majoring in a STEM field.

But, here is where it gets interesting, the effects of higher levels of math performance and perceived ability are much bigger for boys than for girls. Performing in the highest percentiles of the W-J AP distribution, as compared to performing in the lowest percentiles, is associated with an increase in the probability of majoring in a “hard sciences” STEM field of about 13 percentage points for boys but only 6 percentage points for girls. Similarly, reporting the highest levels of perceived math ability, as compared to the lowest levels, is associated with an increase in the probability of majoring in a “hard sciences” field of about 7 percentage points for boys but only 2 percentage points for girls. These results suggest a loss of STEM enrollment by otherwise capable women.  And we can’t simply fix the problem by trying to boost women’s confidence in their true abilities, because women’s confidence contributes less to pursuing STEM than men’s confidence.  Perhaps men are rewarded for over-confidence in a way that women are not.

Interestingly, having a parent who works in a STEM occupation could help girls and not so much boys. The probability of majoring in “hard sciences” STEM fields increases by about 14 percentage points for girls when one of the parents works in a science job. For boys the increase of this probability is only 4 percentage points. Whatever the reason, these results suggest that parental occupation type could be an important factor reducing gender differences.

As for the answer I gave to my daughter, I said “It is not true that girls are bad at math. Look at your mother. My job is doing math all day!” I work on the field of applied econometrics and so, I guess that was close enough.


Public Service Announcement

February 14, 2018

(Guest post by Greg Forster)

Citizens! You are hereby notified that Mary and the Witch’s Flower, which I reviewed here, is returning to US theaters for two days only next week, due to overwhelming demand.

If you missed it the first time, attendance is mandatory. Otherwise, attendance is merely meritorious.

A theater near me has brought back Darkest Hour, the surprise hit of the Oscar noms – perhaps one near you has done so as well. As I said before, you should see that one on the big screen, too!

End transmission.

The Legacy of Andrew Coulson

February 8, 2018

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(Guest Post by Jason Bedrick)

Yesterday marked the second anniversary of the tragically early passing of Andrew J. Coulson, the brilliant and (in the words of his beloved wife, Kay) “happy, effusive, relentlessly upbeat” education reformer, policy analyst, and director of the Cato Institute’s Center for Educational Freedom.

IMHO, the best tribute we can pay to Andrew is to reflect on his ideas. Although he didn’t live to see it, PBS ran his magnum opus documentary, School, Inc., about how and why our education system lacks the progress, innovation, and efficiency gains seen in nearly every other industry. Last year, the Friedmanesque three-part series won the Anthem Film Festival’s award for Excellence in Filmmaking – Documentary Feature, and now Free to Choose Media is making the documentary available to view for free online.

The Cato Institute has also made Educational Freedom: Remembering Andrew Coulson, Debating His Ideas, available to download as a free e-book.

Andrew’s voice is greatly missed in today’s debates over education policy, but as Neal McCluskey wrote, “Thankfully, his ideas remain, and they will always illuminate the pathway forward.”


NOTE: This post has been updated to clarify that it is Free to Choose Media that is making School, Inc. available to watch free online.

Choice Opponent Claims Families Don’t Want Choices

February 7, 2018

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(Guest Post by Jason Bedrick)

Opponents of school choice frequently claim that the sky will fall if a school choice program is enacted. For example, the School Superintendents Association (AASA) claims that choice programs would “‘starve’ public education of critical funding” because so many students would leave their assigned district school in favor of alternatives.

Leaving aside how such concerns treats kids as mere funding units, choice opponents making this claim fail to take into account why families want other alternatives. Indeed, as the Cato Institute’s David Boaz has pointed out, such arguments reveal “the contempt that the [education] establishment has for its own product.”

Perhaps it is a new modicum of self-awareness that prompted a spokesperson of the AASA to abruptly (if unpersuasively) reverse course in a recent interview with EdWeek:

“Conservative think tanks are trying to solve problems that families and communities aren’t asking them to solve through school choice,” said Sasha Pudelski, the advocacy director at AASA, the School Superintendents Association. “When you talk to stakeholders, you don’t hear, ‘Please provide our families with more educational options;’ they want their own schools to be better. They are not looking for an alternative. It’s a solution without a problem.”

So which is it? Either no one is looking for alternative education options, in which case educational choice programs pose no threat because no one will use them anyway, or a significant number of families are looking for alternatives, in which case the district school establishment needs to explain why they shouldn’t have any (or, at least, why those options should only be open to children whose parents can afford them).

In case you were wondering about the answer, I’ll let 100,000+ low-income tax-credit scholarship students in Florida do the talking:


Image: “Rally in Tally” to support school choice on March 24, 2011. h/t Step Up for Students

The Not-So-Wild West in Oklahoma

February 7, 2018


(Guest post by Greg Forster)

While we’re on the subject of the Arizonan wild west, here’s my latest for OCPA’s Perspective on some very non-wild-west Oklahoma school overregulation:

The more prominent strategy, the one that got the most attention and funding, was toward greater centralized control. If schools are given more inputs and they fail to use them to produce better outcomes, then the schools are clearly working to enrich themselves. They can’t be trusted to carry the ball for fixing education.

Who could be trusted? Why, the reformers, of course.

Some interesting information from a state think tank:

The 1889 Institute’s database of public school regulations is the cumulative legacy of these earlier forces and the dramatic increase of regulations in the last generation. It runs to 610 entries. Schools are required to track every individual student’s progress in financial literacy education and every individual teacher’s professional development “points,” spend at least a certain minimum amount on their libraries, and meet test score targets or be subject to sanctions. They must also master obscure laws governing everything from inter-district transfers to the nutritional value of diet soda…

Very few of the regulations in the 1889 Institute’s database deal with issues that really need to be handled at the district level, never mind the state. I honestly think that the nutritional value of diet soda might not even need to be managed by schools at all. But if it does, why not let the principal hire lunchroom staff who are up to the job?

If you want to let me know what you think, the comment section below is not overregulated!

Providing Computers Does Not Improve College Enrollment, Employment, or Earnings

February 6, 2018

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In a fascinating new study by Robert W. Fairlie and Peter Riley Bahr, they examine the effects of an experiment in which some community college students received free computers and others did not by lottery.  Comparing these randomly assigned treatment and control groups, the researchers found that computer skills rose among students who were given computers, but those skills did not translate into higher college enrollment, employment, or earnings for the treatment group.

These results are particularly important because many politicians have focused on improving computer skills as the key to improving educational outcomes.  In Arkansas, the main education policy initiative championed by the governor is a law that requires all public schools to offer computer science classesTexas has adopted a similar policy.  Leaving aside all of the obvious practical concerns, like whether schools have or can develop staff qualified to teach computer science, this new research raises questions about the aim of these policies.  How important is increasing computer skills for the vast majority of students?  No one doubts that most workers have to use computers, but many students may already possess the skills they need and it seems doubtful that raising average computer skills would lead to significant changes in employment outcomes — and that’s assuming we can improve computer skills in a meaningful way.

The new study is also incredibly useful in that it reminds us of how important it is to rely on randomized experiments rather than studies that use matching or controls for observables.  They conclude:

Importantly, our null effect estimates from the random experiment differ substantially from those found from an analysis of CPS data, raising concerns about the potential for selection bias in non-experimental estimates of returns.  Estimates from regressions with detailed controls, nearest-neighbor models, and propensity score models all indicate large, positive, and statistically significant relationships between computer ownership and earnings and employment, in sharp contrast to the null effects of our experiment.  It may be that non-experimental estimates overstate the labor market returns to computer skills.

It is simply false that matching studies are just as good or almost as good as randomized experiments.  Sometimes you get the same result in a matching and RCT study, but that could simply be because selection did not bias the result in that case or you were just lucky.  Sometimes a coin flip will also give you the same result.  Theoretically, we know that selection bias is a serious concern, which means that we can never have strong confidence in research designs that assume selection issues don’t exist.

(edited slightly)

My Charter School in Canada

February 4, 2018

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Matt Ladner and Max Eden have observed that the National Alliance for Public Charter Schools (NAPCS) as well as the National Association of Charter School Authorizers (NACSA) give their highest ratings to states that barely have any charter schools.  As Max noted of the NAPCS rating: “Half the states in the top ten have fewer than 10 charter schools.” He added: “three of your top 10 states have produced 20 schools in 20 years.”

It’s bad enough that there is no evidence to support the criteria that NAPCS and NACSA use to rate state charter laws, but it’s intolerable that their ratings seem to praise policies that are associated with slowing the spread of charter schools — the exact opposite of what these groups are supposed to be advocating for.

It’s nice that Robin Lake is noticing that charter growth has stalled and that Portfolio Management is beginning to block more charter schools in Denver, but somehow neither she nor Paul Hill, nor any of the other charter intelligentsia, seem to be able to connect the dots and trace the problem to the types of burdensome regulatory schemes that they all prefer.  These folks back burdensome regulations with the claim that they help promote charter quality and forestall political problems, even though there is no evidence that they accomplish either of these goals.  But the evidence is becoming quite clear that what these burdensome regulatory schemes accomplish is the creation of very few charter schools and even fewer led by minority members of local communities.

It’s as if the charter intelligentsia thinks that the best charter school is the one that isn’t there.  This reminds me of the Girlfriend in Canada trope.  The best girlfriend (charter school) is the one who isn’t there.  She’s really great and I wish you could meet her, but she lives far away. Avenue Q captured this trope nicely, so I’ve modified the lyrics a bit:

I wish you could go to my charter school
My charter school that’s placed in Canada
The scores couldn’t be higher, I swear I’m not a liar
My charter school that’s placed in Canada
Its leadership is Ivy League, too bad they’re all lily-white
Competitors are not in sight, no one can put up a fight
They test kids every single day, just to make sure that everything’s okay
It’s a pity the school’s so far away in Canada
Last year we reported the highest grad rate
Too bad it’s because we chose to inflate
It’s so sad, that doesn’t mean we’re not great
Our discipline’s progressive and our politics transgressive
I wish you could go to my charter school
But you can’t because it’s in Canada
I know I’m persistent, even if it’s non-existent
That’s why I favor district schools… er, I mean charter schools
Darn, I really want district schools to create more charter schools
It’s the best charter school, my wonderful charter school
Yes, I have a charter school that’s placed in Canada
And I can’t wait to give kids more choices