Unaccompanied Minors and Causation

The puzzle over the surge of unaccompanied minors is tied directly to the difference between correlation and causation. The essential problem is understanding the surge. On one side--usually associated with the Republican Party--the argument is that President Obama's promises about deferred action acted as a catalyst. From Senator Ted Cruz:

Is it really your testimony that granting amnesty to some 800,000 people who came here illegally as children had no effect in causing a dramatic increase of children being handed over to international drug cartels to be smuggled in here illegally?

There are problems with that when we start trying to move from correlation to causation.

First, the timing is off. From Adam Isacson:

Border Patrol statistics, depicted above, show that arrivals of unaccompanied Central American children began increasing during U.S. fiscal year 2012, which ran from October 2011 to September 2012. DACA was not announced until June 2012. Immigration reform legislation had not yet been proposed, and the review of deportation procedures was far off. In fact, in 2012 the Obama administration broke the United States’ single-year record for deportations of undocumented foreign citizens (409,849 people): hardly a welcoming message for would-be migrants.

Second, there is no evidence that immigrants knew about DACA at all. From Elizabeth Kennedy, who was doing fieldwork:

“The rumors did not start until Obama called it an urgent humanitarian situation,” she said. “In over 300 interviews, only one asked about DACA [Deferred Action for Childhood Arrivals]. Otherwise, no one ever named any specific U.S. legislation. Some asked if children should lie about their age and say they were over 18.” 

Third, if rumors about DACA are rampant, why are there so few sending countries? From federal officials:

Federal officials have said that if migrants were coming to the U.S. because of the DACA program, there would be many more families arriving from countries other than Honduras, El Salvador and Guatemala — such as India and China — to also take advantage of the program.

There is no surge from Mexico, for example, which makes no sense if this logic is to hold. Incentives like DACA would spread southward through Mexico, yet somehow affect only Central America.

On the other side of the debate, violence in Central America is blamed. From Tom Wong:

Violence is among of the main drivers causing the increase. Whereas Central American countries that are experiencing high levels of violence have seen thousands of children flee, others with lower levels of violence are not facing the same outflow.

He equates "violence" with "homicide." Mike Allison notes that homicide rates have actually improved so cannot explain a surge, and attributes emigration to gang violence instead:

What seems to be a better explanation for what is driving people to leave their homes is the threat from the Mara Salvatrucha (MS-13) and 18th Street gangs that have been operating in Central America for two decades. Violence worsened in the 2000s when governments adopted mano dura ("strong hand") security policies rather than investing in social programmes, education, and gang prevention and rehabilitation strategies. Regional drug cartels and gangs have grown increasingly powerful as the region has become a much more important transit point for drugs.

This is really hard to measure, though. If the "mano dura" approach was taken a decade or so ago, how do we explain the lag?

Correlation is easy to find, causation much harder. I probably buy Mike's hypothesis more than any other, but even then I would have to see more data to be convinced. It's a sad, tragic, and still largely unexplained phenomenon.