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This is getting old. I find myself correcting false claims regarding the scientific evidence on private school choice all too often. For example, using only one correlational study that did not detect any statistically significant effects, Valerie Strauss recently concluded that “private schools aren’t better at educating kids than public schools” in the Washington Post. As I have pointed out many times before, the preponderance of the causal evidence indicates that school voucher programs in the U.S. improve student test scores and more important outcomes such as high school graduation, college enrollment, and tolerance of others.

But science shouldn’t determine whether families are allowed to pick the schools they want for their kids.

Just imagine if we used the scientific evidence to decide whether people should be residentially assigned to their nearest government grocery store. What if we randomly assigned thousands of families to government-run grocery stores and found that, on average, those families consumed fewer calories than the families with the freedom to shop for groceries on their own? Such an empirical finding certainly wouldn’t mean that the government should compel all individual families to accept the grocery basket deemed ideal by the experts. After all, a crude metric such as caloric intake can only tell us so much about how well an individual’s nutritional needs are being met. And, of course, some people may simply value eating appetizing foods more than the benefits of having a lower BMI. It would be a disgraceful limitation of freedom to compel people to consume—and pay for—a basket of groceries they did not want.

Yet this is precisely the type argument often used against freedom in education—that parents are somehow unfit to choose schools for their own kids.

But it’s worse than that with education because most of the random-assignment evaluations find that students are better off when their parents are allowed to choose their schools. And even though the most rigorous scientific evidence available says families should have school choice, less than one percent of the school-aged population in the U.S. uses a private school choice program.

But why shouldn’t society use science to force other people to do the “right” things?

Of course, science can tell us a lot about the world around us. And random assignment (the “gold standard” of scientific research) is the best thing we have available to determine how certain treatments (or policies) affect groups of people. However, even the best methodology has important flaws that do not allow researchers to give central planners enough information to make good decisions for individual families.

For example, since the internal validity of experimental design relies on something called the law of large numbers, the methodology only allows researchers to determine the average effects of policies for large groups of people. In other words, even the best scientific methodology that exists cannot determine the effect of policies on specific individuals. And then there is the external validity problem—even if a school choice program is found to have large positive (or negative) effects on one group of students, on average, it is unlikely that the effects will be exactly the same for the other cohorts of students or in different settings. Similarly, the effectiveness of school choice programs—and the supply of private schools—can change over time.

And education technocrats frequently use faulty measures of success—standardized test scores—because it is extremely difficult for researchers to get their hands on more important long-term outcomes such as earnings, crime, and character skills. The main problem is that effects on math and reading test scores often do not predict effects on more important long-term outcomes. For instance, a recent American Enterprise Institute review of the evidence found that 61 percent of school choice programs’ effects on math test scores—and 50 percent of effects on reading test scores—did not predict effects on high school graduation. And at least 11 other studies have found divergences between private schools’ effects on test scores and their effects on more important long-term outcomes. For example, a peer-reviewed evaluation found that private school vouchers in Ohio had no effect on test scores but increased students’ charitable donations by 23 percent. In other words, focusing too much on standardized test scores could compromise the character skills necessary for true lifelong success.

And that’s just the tip of the iceberg. Many evaluations do not use random assignment—and the problems only get much worse when weaker empirical methods are used. Put simply, central planners face a severe knowledge problem with education today—just as central planners faced severe knowledge problems with five-year plans in the Soviet Union.

The fact is that families have more information about what their individual children need than education bureaucrats and scientists sitting in offices—hundreds of miles away. Families are also more interested in their own children’s lifelong success than anyone else.

The strongest scientific evidence we have on the subject suggests that private school choice works. But that really shouldn’t even matter. Just as people have the right to pick their own groceries, people should have the right to pick the schools that they believe will work best for their own kids. And just as government officials cannot force families to eat at particular restaurants, government officials shouldn’t be able to force families to send their kids to failing government schools.

Late yesterday, U.S. District Court Judge Robert Lasnik issued a temporary restraining order (TRO) blocking the release of design files for 3D-printed guns. The order comes in response to a lawsuit filed by a number of state attorneys general who claim that the Trump administration acted unlawfully in reaching a settlement in a lawsuit brought by Defense Distributed, a company that produces digital blueprints for 3D-printed guns, and the Second Amendment Foundation. Judge Lasnik found that states were likely to suffer irreparable harm—the standard for a TRO—if the digital blueprints became distributable via a website, and he felt that the situation was such an emergency that the order was issued within a day of when the suit was filed.

This is a deeply silly order. People have been making guns out of various objects for centuries. Watch this video of someone making a shotgun out of two pieces of commonly available tubing.

Zip guns like those have been used for centuries. They’re easy to make and easy to learn how to make. And, as long as you follow certain guidelines (such as not making a machine gun), such guns are perfectly legal to make. As the ATF website says: “No, a license is not required to make a firearm solely for personal use.”

Moreover, distributing plans for zip guns is a form of speech protected by the First Amendment, as it should be. Here’s a website telling you how to make one, and here’s a YouTube video telling you how to make one in less than two minutes. Judge Lasnik’s TRO is the equivalent of shutting down those websites and videos because telling people how to make zip guns creates an “irreparable harm.”

3D-printed guns are little better than those zip guns. The Libertor is a one-shot pistol that, if it works, fires a low-powered bullet with an effective range of maybe 20 feet. More often, it might just explode in your hand. As one commentator writes,

The Liberator’s bullet emerges going very slowly and wobbling or tumbling due to lack of spin. It might go almost anywhere, though not very far, and is unlikely to do much damage to anything it manages to hit. It’s a bit better than holding up a cartridge in a pair of pliers and banging the cap with a centrepunch or similar, but not much.

The Songbird is another design that works slightly better, but still wouldn’t be your first choice for doing anything except demonstrating to your friends that you built a gun that doesn’t blow up in your hand.

These guns are little better than a musket or a muzzle-loading flintlock pistol, which anyone can purchase without a background check. Yes, that’s right, criminals all over the country can purchase something like this replica English Civil War cavalry pistol and wreak havoc. Sure, they’ll need to get some black powder, some wadding, and some musket balls, but those are widely available, especially in the internet age. Or, if they want more than one shot, they can purchase this 1860 model Colt revolver replica, also without a background check, which would certainly be good enough to rob a store. So why aren’t people constantly robbing stores with the guns of Jesse James or Captain Jack Sparrow? Because it would be stupid and more expensive than purchasing this professionally manufactured Hi-Point 916 for $149.00. And if someone is prohibited from purchasing a gun from a licensed dealer, perhaps because they’re a convicted felon, they can acquire a gun in the myriad ways criminals acquire guns. No street-level gun dealer is waiting for the TRO to be lifted so he can start flooding the streets with in-demand single-shot plastic pistols. The concept is too silly to contemplate.

The idea that allowing websites to distribute digital blueprints for 3D-printed guns creates “irreparable harm” to the states is as silly as saying allowing people to distribute plans for zip guns does “irreparable harm.” The fear created by the phrase “3D-printed guns” should not be allowed to override common sense.

The usual narrative is that Democrats support consumer protections and Republicans oppose them. Today’s short-term plans final rule flips that narrative: Republicans are expanding consumer protections, and Democrats are opposing them.

Today’s rule reverses a 2016 Obama rule. The Obama rule reduced consumer protections in short-term plans by exposing sick patients to medical underwriting. Before that rule, consumers could purchase short-term plans that lasted 12 months. If they developed a serious illness, their plan could cover them until the next ObamaCare open enrollment period, when they could purchase coverage without medical underwriting. The Obama rule restricted short-term plans to 3 months. It prohibited “renewal guarantees” that protect enrollees who fall ill from medical underwriting when they purchased a new short-term plan. As a result, the Obama rule left short-term plan enrollees who got sick with no coverage for up to 9 months: those who purchased a plan in January, and developed a serious illness in February, would lose their coverage at the end of March, and have no coverage until the following January. (Source: NAIC) This was by design: the Obama administration wanted to expose sick people in short-term plans to medical underwriting and lost coverage as a way of forcing consumers to buy ObamaCare coverage instead. That’s at least a little messed up.

Today’s rule allows short-term plans to last 12 months and offer renewal guarantees. It therefore allows short-term plans to protect the sick from medical underwriting for an additional 9 months—indeed, “issuers may offer coverage under a short-term, limited-duration insurance policy for up to a total of 36 months, without any medical underwriting or experience rating beyond that completed upon the initial sale of the policy”—and allows renewal guarantees to protect them from medical underwriting indefinitely. Protecting the sick from medical underwriting has long been a goal of Congress.

So, to recap, Republicans are expanding consumer protections, and Democrats are opposing an expansion of consumer protections.

Weird, isn’t it?

President Trump tweeted this morning that, “One of the reasons we need Great Border Security is that Mexico’s murder rate in 2017 increased by 27% to 31,174 people killed, a record! The Democrats want Open Borders. I want Maximum Border Security and respect for ICE and our great Law Enforcement Professionals!”  He tweeted this because he’s spent the last few days stating that he would shut down the government if Congress did not adopt his immigration proposed reforms in the upcoming budget debate, especially the funding for the construction of a border wall.

Besides the political motivation for his tweet, President Trump seems to have assumed that crime in Mexico bleeds north into the United States, so more border security is required to prevent that from happening as murder rates begin to rise again in Mexico.  Although illegal immigrant incarceration rates are lower than they are for natives, illegal immigrant conviction rates in the border state of Texas are lower for almost every crime including homicide, and the vast majority of evidence indicates that illegal and legal immigrants are less crime-prone than natives, the President’s specific claim that murder rates spread from Mexico to the United States is different from most of the existing peer-reviewed literature. 

My colleague Andrew Forrester and I ran some simple regressions to test whether higher homicide rates in Mexican states that border the United States spread northward to U.S. states on the other side of the border.  It doesn’t make much sense to compare Mexican crime in the Yucatan Peninsula with that in Maine but, if President Trump’s theory is correct, then we should expect to see it cross from Baja California to California, for instance.  Homicide data for the Mexican border states come from the Mexican National Institute of Statistics and Geography.  American homicide data come from the Uniform Crime Reporting statistics at the FBI (files here).  Homicide rates in states in both countries are per 100,000 state residents which allows an apples-to-apples comparison.  We used data from 1997 through 2016 but were not able to include 2017 as U.S. crime data is unavailable for the American states although it is available for the Mexican states.  We decided to look exclusively at U.S. and Mexican border states because those are where we would expect crime to bleed over if such a thing happened. 

Figure 1 shows a negative relationship between homicide rates in U.S. border states and Mexican border states with a negative correlation coefficient of -0.46.  The coefficient is nearly identical when Mexican homicide rates in the previous year are compared to American homicide rates in the following year.  Although we did not include other controls, there is a negative relationship between homicides on the American side and the Mexican side.  In other words, when Mexican homicide rates go up then American rates tend to go down and vice versa.     

Figure 1

Homicide Rates in U.S. and Mexican Border States, 1997-2016

Homicide Rates in U.S. and Mexican Border States

Sources: UCR and NISG.

Note: Rates are per 100,000 residents in each state.

Figure 2 shows the same data but with years on the X-axis.  Mexican border state homicide rates vary considerably over time, especially when that government decided to try to crack down on drug cartels, but U.S. border state homicide rates trended slowly downward over the entire time.  There is a negative relationship between Mexican homicide rates and homicide rates in U.S. border states. 

Figure 2

Homicide Rates in U.S. and Mexican Border States, 1997-2016

Homicide Rates in U.S. and Mexican Border States

Sources: UCR and NISG.

Note: Rates are per 100,000 residents in each state.

Our figures and regressions above might not be capturing the whole picture.  Perhaps crime travels from Mexican border states and goes directly into the U.S. state that it is bordering.  That could be the source of President Trump’s worry.  We tested that in Figures 3-6 where we looked at how homicide rates in Mexican states contiguous to U.S. states are correlated with homicide rates there. 

Figure 3 shows homicide rates in the Mexican state of Baja California and in the American state of California.  There is a negative correlation coefficient of -0.66 between homicide rates in Baja California and in California, meaning that homicide rates move in the opposite directions in these two states.    

Figure 3

Homicide Rates in California and Baja California, 1997-2016

Homicide Rates in California and Baja California

Sources: UCR and NISG.

Note: Rates are per 100,000 residents in each state.

Figure 4 compares homicide rates in Arizona with those in Baja California and Sonora.  Homicide rates between Baja California and Arizona have a correlation coefficient of -0.69, meaning that homicide rates in Baja California and Arizona generally move in opposite directions.  Homicide rates in Arizona and Sonora have a correlation coefficient of +0.20, which means that they somewhat move in the same direction. 

It’s important to point out that the Sonoran homicide rate moves in roughly the same direction as Arizona’s homicide rate because Sonora’s rate mostly declines over the entire period and varies little by year just as Arizona’s rate does.  The Sonoran homicide rate will most closely track homicide rates in other American states for that reason but that does not show that Mexican murderers are crossing the border because Sonora is not as affected by the violent homicide swings that seem to dominate homicide rates in other Mexican states.  The Sonoran homicide rate comoves with Arizona’s homicide rate since they are both less volatile over time.    

Figure 4

Homicide Rates in Arizona, Baja California, and Sonora, 1997-2016

Homicide Rates in California and Baja California

Sources: UCR and NISG.

Note: Rates are per 100,000 residents in each state.

Figure 5 shows that homicide rates in New Mexico are positively correlated with those in Sonora at Chihuahua with coefficients of +0.40 and +0.05, respectively.  New Mexico’s homicide rate is more erratic and has a higher standard deviation than the other American states. 


Figure 5

Homicide Rates in New Mexico, Chihuahua, and Sonora, 1997-2016

Homicide Rates in New Mexico, Chihuahua, and Sonora

Sources: UCR and NISG.

Note: Rates are per 100,000 residents in each state.

Homicide rates in Texas are negatively correlated with homicide rates in the Mexican states of Coahuila, Nuevo Leon, and Tamaulipas with correlation coefficients of -0.79, -0.79, and -0.36, respectively.     

Figure 6

Homicide Rates in Texas, Coahuila, Nuevo Leon, and Tamaulipas, 1997-2016

Homicide Rates in Texas, Coahuila, Nuevo Leon, and Tamaulipas

Sources: UCR and NISG.

Note: Rates are per 100,000 residents in each state.

Correlation is not causation, especially in these simple regressions, but it would be very difficult to show that Mexican homicide rates are driving or at least influencing those in U.S. border states without at least finding a positive correlation.  The p-values in all of the above figures are all so high that the correlations are statistically insignificant in every case.  Researchers should dig into this data further to tease out more precise estimates or effects, but they are not significant or interesting enough for us to spend more time on them.  There are, of course, individual circumstances of Mexican criminals committing crimes in American states but that does not tell us how common those events are or whether President Trump’s proposed solutions would have any impact.  If the past events are any indication of the future, our work above allows us to confidently say that there is little reason to worry that homicide rates in Mexican border states will influence homicide rates in U.S. border states.  Whatever potential justifications there are for an expensive border wall, preventing the spread of homicide northward shouldn’t be one of them.      

Special thanks to Andrew Forrester for his help in writing this piece.      

Although many hailed last week’s “trade agreement” between President Trump and European Commission President Jean-Claude Juncker as an important achievement, it included no firm commitments to reduce tariffs, non-tariff barriers, or subsidies—or to do anything for that matter. The only agreement of substance was that new tariffs would not be imposed, while Washington and Brussels negotiated longer-term solutions to problems both real and imagined.

Those hungering for some good trade news might call that progress, but the only new tariffs that were under consideration (outside the exclusive domain of the president’s head) were those related to the Commerce Department’s investigation into the national security implications of automobile and auto parts imports. Of course, that investigation is still proceeding and there’s no reason to think Trump won’t leverage the threat of imposing auto tariffs to bend the outcome of those EU negotiations in his favor.

So what does Trump want? Trump seems committed to prosecuting a trade war with China and he expects the EU to have his back in that fight. Trump’s tariffs on $34 billion of Chinese products are scheduled to expand to $50 billion in early August and potentially to $250 billion in September. In a recent CNBC interview, Trump even threatened to subject all Chinese goods—more than $500 billion worth of imports in 2017—to additional tariffs.

For the first $34 billion, China has retaliated in kind, targeting mostly agricultural, aquaculture, and meat products. Beijing has pledged to go tit-for-tat throughout, even though its retaliation would have to take other forms—such as penalizing U.S. multinationals operating in China—because annual U.S. exports to China are in the neighborhood of only $130 billion.

The only real factor constraining Trump’s trade war is the potential that workers in red states will abandon the cause and turn on him. But so far, even as domestic production and employment are threatened as a consequence of the tariffs and the retaliation, Trump’s base still seems to be supporting his unorthodox, zero-sum approach to trade. Last month, a worker at Wisconsin’s Harley-Davidson facility, which will be downsizing as the company shifts production to Europe as a result of the EU’s retaliatory tariffs, said of Trump: “He wouldn’t do it unless it needed to be done, he’s a very smart businessman.” That worker and many others agree that the United States should be throwing its weight around to obtain a larger slice of the pie—even if that process ends up reducing the overall size of the pie.

In a effort to fortify that support, last week the administration authorized $12 billion of emergency relief for U.S. farmers caught in China’s retaliatory fire. Plans for financial relief for other industries similarly imperiled by retaliation are likely in the works and Trump expects the EU to do its part by picking up the slack and purchasing more U.S. soya, natural gas, and other commodities and manufactures previously destined for China. 

That may seem presumptuous, given that Trump has hit Europe with steel and aluminum tariffs, threatens her with auto tariffs, and called Europe a foe on the eve of his Helsinki meeting with Putin. Why would the EU oblige? That would seem to only encourage more of Trump’s passive-aggressive behavior.

Well, first, the EU wants to avoid the auto tariffs, which threaten the global auto market and, second, it shares many of the same concerns about China’s trade practices. But there’s only so much Europe can do to absorb excess U.S. supply. Will Trump insist that Germany cancel its gas contracts with Russia?  That would be an interesting twist. Will it be enough? Or will Trump deem the EU ungrateful and kill the auto trade?

The best we can hope for, I think, is that Trump comes to realize that if he wants to apply effective pressure on Beijing to abandon its most objectionable policies and to open its markets without onerous conditions, he will need the support—not the ire—of the governments of the EU, Japan, Korea, Canada, and Mexico to compel China to play by the rules. That means ditching the steel and aluminum tariffs and making nice. Then, maybe Trump will recommit the United States to abiding by those rules, too.



Concerned with how trade is commonly discussed, Greg Mankiw recently issued a plea to journalists to halt the use of subjective terms to describe trade flows. Rather than words such as “deteriorated” or “improved,” the Harvard economics professor (and noted textbook author) proposes that writers employ more objective language such as “the trade balance moved towards surplus.”

Mankiw’s plea is fine as far as it goes, but it probably doesn’t go far enough. The problem in the way trade is discussed lies not only in the descriptions applied, but the nouns themselves.

To speak of trade surpluses or deficits is utterly nonsensical, or at the very least a corruption of the term “trade” that incorrectly uses it as a synonym for “exports.” Trade, however, comprises both selling and buying, both exports and imports. The amount of trade between two countries (or any other group of entities) is the sum of their exports and imports. Given that both sides engage in the same amount of bilateral trade—that is to say, the same total of exporting and importing—a trade deficit is a mythical beast and logical impossibility. Perhaps we can speak of net exports or net imports, or export deficits and import surpluses as well as their reverse, but “trade deficit” should be regarded as a term devoid of real meaning.

Talk of a trade balance either being in surplus or deficit is problematic for similar reasons. Occasionally, one may encounter the descriptor “positive” applied to the trade balance if exports exceed imports and “negative” if the opposite occurs. But—as with trade deficits and surpluses—this is completely arbitrary. It makes no more sense to say this than to characterize a surplus of imports as positive or exports exceeding imports as negative.

This is no exercise in pedanticism. Precision of language is important. Terms matter, and the way in which trade is discussed influences how it is perceived. One can’t help but wonder how many people have an irrational fear of imports because they are said to contribute to a “trade deficit” or a “negative trade balance”—terms laden with unfavorable connotations. It’s not difficult to imagine that U.S. trade policy would be on a very different trajectory if President Trump spent his formative years in a world that did not speak of trade deficits and instead used more exact language and terms.

It may be too late for Trump, but a change in terminology could go a long way toward improving the conversation around trade and clearing the path for better policy.

Former White House national security official and Hillsdale College lecturer Michael Anton wrote an op-ed recently in the Washington Post where he used falsified quotes, poor legal reasoning, and displayed ignorance of the history and debates surrounding the 14th amendment to argue that President Trump should unilaterally end birthright citizenship (here’s Anton’s poor response to the devastating criticisms). 

Few commentators discussed what the actual effects of removing birthright citizenship would be and instead focused on the comparatively unimportant legal questions.  As an exception, my piece for the American Conservative argued that such a move would diminish immigrant assimilation in the United States.  However, I neglected to mention any of the social science that backed up my assertion in the American Conservative.  Below is a short summary of the relevant literature of the evidence that birthright citizenship helps immigrant assimilation.   

There are more assertions that birthright citizenship helps immigrant assimilation and integration than there are individual research papers testing the claim.  The major measures of assimilation or integration, both internationally and domestically, consider citizenship important.  The National Academies of Sciences (NAS) mammoth literature survey on the integration and assimilation of immigrants in the United States mentions birthright citizenship but never cites research backing up assimilations claims.  “Birthright citizenship is one of the most powerful mechanisms of formal political and civic inclusion in the United States,” the report says without any supporting evidence.  Later, the authors state, “Birthright citizenship is one of the most powerful mechanisms of formal political and civic inclusion in the United States; without it, the citizenship status of 37.1 million second-generation Americans living in the country (about 12% of the country’s population), and perhaps many millions more in the third and higher generations, would be up for debate.”  Again, the report does not provide any support for how powerful a mechanism for assimilation birthright citizenship is except to show that many people born here would not be citizens. 

Perhaps the NAS report doesn’t report on how citizenship affects assimilation and integration because the United States has had birthright citizenship for a long time.  Because of that continuity of policy, there is no experiment to run in the United States to test the importance of birthright citizenship for assimilation.  However, there are three suggestive pieces or strands of literature in the American context.  The first is Immigrants Raising Citizens where the author, Hirokazu Yoshikawa, writes that citizenship confers enormous benefits on the children of immigrants but the non-citizen status of their parents limits their ability to help them succeed. 

The second piece is the academic literature (see ft. 9) that shows that earning legal immigration status through an amnesty or DACA, even if it results in a status less than citizenship, confers enormous assimilative and economic benefits on the beneficiaries.  DACA and amnesties are better experiments to test the importance of citizenship or legal status by itself rather than normal naturalization because studies of the former policies remove the endogeneity concern while studies of the latter variety are plagued by it.  That’s a concern because people who choose to naturalize are probably different than those choosing not to, and those differences probably explain assimilative or economic outcomes better than the actual grant of citizenship.

The third piece, a book chapter by Irene Bloemraad, has a section based on interviews with many U.S.-born children of immigrants and what they think it means to be an American.  A common answer is that being born in the United States makes them an American.  One respondent said “we are all 100 percent Americans, we were born here. No matter what people say, we are Americans.”   Another telling exchange went like this:

One Vietnamese American teen’s response was typical.  Asked why he thinks of himself as America, he seemed a bit puzzled and said, “Because I was born here.”  This sort of response – repeated among a fair number of the teens – did not involve discussion of civic principles of cultural habits.  U.S. birth was enough or this teen to feel like he was American.

The third sentence of that quote may worry some folks concerned about the assimilation of the children of immigrants, but I doubt almost any other American-born teen would have answered differently.  Compared to Real Americans and not to the Imagined Americans of nationalist lore, birthright citizenship appeared to have helped here. 

However, the United States is not a great place to study the effects of birthright citizenship because we have not had a shift or reinterpretation in those rules in over a century.  Some countries like Ireland, the Dominican Republic, and Germany, have recently changed their citizenship laws to restrict birthright citizenship, also known as jus soli, and provide a quasi-natural experiment to study these effects

Germany provides the best opportunity to study the effects of birthright citizenship on assimilation.  The German Citizenship and Nationality Law of 1913 only granted citizenship to those who had at least one parent who was a German citizen at the time of the child’s birth.  In 1999, the German parliament amended that law to create a birthright citizenship component for children born on January 1, 2000, or after if at least one parent had been ordinarily resident in the country for at least eight years.  The law also created a transition period for many children born from 1990 through 2000 to naturalize if they met the requirements of the new law. 

This change in German citizenship law prompted a flood of research on how the new law affected immigrant assimilation in Germany.  Economists Ciro Avitabile, Irma Clots-Figuera, and Paolo Masella looked at how the new German law affected parental integration in a peer-reviewed paper published in the prestigious Journal of Law and Economics.  Their paper used responses from the German Social Economic Panel Survey to see how immigrants whose children were affected by the new citizenship law changed their behavior relative to those unaffected by the change in the law.  It focused on measurements of interactions with Germans (visiting or being visited by a German in a social situation), speaking German, and reading German newspapers.  On all three metrics, the immigrant parents of children who could naturalize became more integrated. 

The effects were small but noticeable.  The percentage of immigrant parents who had interactions with Germans rose from 71 percent prior to the reform to 77 percent afterwards, spoken German ability rose from 65 percent prior to the reform to 69 percent afterwards, and reading of German newspapers increased from 2.6 to 2.9 on a five-point scale (1 is home country papers only and 5 is German papers only).  Importantly, the measure of speaking German doesn’t control for fluency.  They also found that the outcomes are larger for immigrants who came from a country that speaks an Indo-European language.  Importantly, Turkish is not an Indo-European language.  For those from a non-Indo-European language group, the reform had no effect on language but it increased their interactions with Germans to the same degree as for the Indo-European language users.  

Taking a wider view of the impact of this law in Germany, Ciro Avitabile, Irma Clots-Figuera, and Paolo Masella, the same economists mentioned above, published a peer-reviewed paper in the American Economic Journal: Applied Economics that looked at how child citizenship laws affected fertility decisions amongst immigrants.  Fertility is influenced by culture, so many social scientists and economists think it is an important indicator of immigrant assimilation.  Consistent with Gary Becker’s “quality-quantity” model of fertility, they found birthright citizenship reduced immigrant fertility and improved their health by reducing obesity and the social-emotional outcomes of the children affected.  Again, the effects are small but citizenship reform moved immigrants closer toward German fertility and health norms.

Gathman, Keller, and Monscheuer also looked at fertility and family structure.  They found that within 7.2 years of eligibility for citizenship, the immigrant-native fertility gap fell by 20 percent by raising the age of first births to immigrant mothers and reducing the likelihood of them having children.  The citizenship reform also narrowed the marriage gap between German and immigrant women by 45 percent and German and immigrant men by 50 percent.  Immigrant women were also more likely to marry men who were not from their own country of origin after the reform but the effect was small.

Felfe, Rainer, and Saurer found that immigrant parents enroll their children in preschool at a higher rate after the citizenship reform, closing the gap with native Germans.  They also enrolled them earlier in primary school and pushed their children into the university track at higher relative rates.  Further, reported “attention deficits” and “emotional problems” for the children of immigrants also decreased in schools relative to natives while there was no effect on reported “social problems,” “German language proficiency,” or “school readiness.”  Another working paper by Felfe, Kocher, Rainer, and Siedler found that the educational achievement gap between young immigrant men and their native peers nearly closes due to the reform.

The granting of citizenship to immigrant children also reduces return migration, increases the rate of mothers stay at home with their children among the parents whose children were affected, and reduces or almost closes the trust gap between immigrant children and native children in behavioral experiments – virtually eliminating in-group favoritism for immigrant boys.  

The relatively few cases of citizenship laws changing in countries with large numbers of immigrants limit the opportunity to study how immigrants and their children are affected by birthright citizenship.  The United States has not changed its policy on birthright citizenship in over a century so any attempt to study the impact of jus soli here would be constrained to cross-country comparisons.  However, legal changes in Germany provided a quasi-natural experiment with the result that birthright citizenship slightly improves immigrant assimilation and integration but it is not, by any means, a panacea.  The evidence from research on how birthright citizenship affects assimilation shows a generally positive impact and policymakers should assume that ending the practice in the United States will negatively affect assimilation here.