Sunday, October 29, 2017


I looked for surveys that were relevant to the issues discussed in my last post, and found one sponsored by CNN and conducted by the Opinion Research Corporation in 2010.  It included a series of questions on whether people favored or opposed:

a. Building a 700-mile long fence on the border with Mexico
b. Creating a program that would allow illegal immigrants already living in the United States for a number of years to stay here and apply to legally remain in this country permanently if they had a job and paid back taxes
c. Imposing fines of tens of thousands of dollars on employers who hire illegal immigrants
d. Sending employers who hire illegal immigrants to jail 
e. Putting more Border Patrol and federal law enforcement agents on the U.S. border with Mexico

The distribution of opinions:

                            Favor        Oppose     Mixed/DK
Fence                    45%           55%          1%
Stay                       83%          17%           0%
Fines                     62%           38%           1%
Jail                        41%           59%           0%
Border                   78%           21%           0%

The survey also contained a series of questions asking about whether certain statements apply to immigrants moving here in the past ten years:

a. Are basically good, honest people (82% say yes)
b. Add to the crime problem (58% yes)
c. Take jobs away from Americans  (52% yes)
d. Are hard-working (87% yes) 
e. Are a burden on American taxpayers (65% yes)

Questions a, c, d, and e from the first group all involve enforcement of immigration laws.  If you add them together to get an index of support for more vigorous enforcement and regress them on the views of immigrants, all have a statistically significant relationship except the first.  That is, there is no evidence that whether or not people think most immigrants are "basically good, honest people has any connection to support for stronger enforcement (the t-ratio is about 0.4) of policies against illegal immigration.  If you regress the "path to citizenship" question (b) from the first series on the same views of immigrants, "basically good, honest people" has a significant relationship (t=3.2), and appears to be the second or third strongest predictor, depending on how you measure.  That is, views of the character of immigrants matter for opinions about whether they should be allowed to stay, but not (or not nearly as much) for opinions about stronger enforcement of the immigration laws.  This pattern illustrates a point I've made before, which is that there are (at least) two immigration issues, and that people who favor stronger enforcement of immigration laws are not necessarily "anti-immigrant" in a general sense.

I didn't find any survey questions that directly involved rights to immigrate or exclude immigrats, but an opinion piece appeared in the New York Times today (it's been online for a few days) about unaccompanied children fleeing violence in Central America and trying to enter the United States.  There are currently about 350 reader comments, and I looked at the ten most liked ones.   None of the them questioned the individual accounts or said that they represented only a small fraction of illegal immigrants. Nine offered some variant of "the United States can't (or doesn't have an obligation) to take in everyone"--the other one said that Mexico was the closest neighbor, so they had the primary responsibility to help.  Although the most liked comments have no value as a measure of the general distribution of opinions, I think they say something about how people explain the opinions they have. 

[Data from the Roper Center for Public Opinion Research]

Tuesday, October 24, 2017

The policy that dare not speak its name

A summary of public opinion on immigration:
1.  Strong majorities think that people who were brought here as children should be allowed to become citizens.  Majorities say that people who came as adults who have been working and don't have a criminal record should at least be allowed to stay, and possibly to become citizens.
2.  Opinion is now pretty evenly divided on whether the level of legal immigration should be increased, reduced, or kept the same.  
3.  Large majorities say that immigration laws should be more strongly enforced about people who are now trying to come in.  

That is, give a break to people who are currently here, but try to stop further illegal immigration.  The policy of the Obama administration was pretty much in line with prevailing public opinion--he supported a proposal for a "path to citizenship," established DACA, left the laws on legal immigration alone, and deported a lot of people.  However, he didn't say much about the deportations.  The attention came from critics, mostly on the left, but including Donald Trump in one of the debates:  "President Obama has moved millions of people out. Nobody knows about it. Nobody talks about it. But under Obama, millions of people have been moved out of this country. They've been deported."  Hillary Clinton said even less about them--as I recall, she just ignored Trump's statement.  Why not talk about a policy that would be popular and refute Trump's claims about how we had "open borders"?  There were some immediate reasons, which are discussed in this article.  But I think there was also a deeper reason.  

In popular moral thinking, nations are important.  We have obligations to other members of our nation that we don't have to people in other nations.  That raises the question of who is a member of our nation.  Regardless of their views on what the right level of immigration should be, the great majority of people would agree that "we" (the current citizens) have a right to decide on their number and the conditions of joining our nation.  If you asked people to give reasons for these beliefs, I think most would say that they are just common sense.

What you could call "sophisticated" thought is not satisfied with appeals to common sense--it demands justification in terms of principles.  Sophisticated thought is not limited to intellectuals in a narrow sense--it also includes most journalists and politicians, and a significant number of educated people more generally.  The major principle that is accepted today is human rights:  people are endowed with certain inalienable rights, among which are life, liberty, and the pursuit of happiness.  Nations and governments are just a means to secure these individual rights.  Living where you want is a basic part of liberty and the pursuit of happiness, so on a straightforward interpretation of this principle, it's hard to justify any restrictions on immigration.  At the same time, most sophisticated people also share the intuitive sense that the nation is more than just an instrument for securing individual rights.  By and large, they deal with this conflict by avoiding it:  Democrats denounce anti-immigrant policies but don't say much about what they think immigration policy should be, and Republicans call for the "rule of law" but don't try to give a justification for those laws.  

I can't offer any direct evidence for any of this, but I think it is a way to make sense of a number of things about public opinion and politics today.   

Tuesday, October 17, 2017

Raise the bar?

A paper published in Nature Human Behavior proposes changing "the default P-value threshold for statistical significance for claims of new discoveries from 0.05 to 0.005"--in terms of t-ratios, from about 2 to 2.8.  The paper seems to have been written with experimental social psychology in mind, but its 72 listed authors include economists, political scientists, and sociologists.  They are a distinguished group--the sociologists are from the University of Pennsylvania, Univ of North Carolina, Michigan, Harvard, Princeton, and Stanford. 

The core argument of the case is about the chance of "false positives."  The great majority of the hypotheses proposed in the social sciences are of the form "x is associated with y" (controlling for other factors relevant to y).  If the observed data would be unlikely under the "null hypothesis" that "x is not associated with y" (controlling for other factors), you count it as support for the hypothesis that "x is associated."

Suppose that for every ten proposed hypotheses that are true, there are 100 that are false.  Using a .05 level means that we can expect a statistically significant association for five of the false ones.  Suppose a statistically significant association is found for 80% of the true hypotheses, which is the target that people usually aim for in designing experiments; then 5 out of 13, or almost 40% of the statistically significant associations will represent false hypotheses.  Their idea is that researchers should change the standard of statistical significance to 0.5% and continue to aim for 80% power (which would mean bigger experiments).  That would mean there would continue to be 8 statistically significant associations that represent real ones but only 0.5 (6% of the total) that are spurious.

The ratio of true to false proposed hypotheses is crucial here.  If it's 1:1, then with 80% power and a 5% significance level, we have only 6% spurious associations.  The authors offer some evidence that the ratio is about 1:10 for psychology experiments, and say that a "similar number has been suggested in cancer clinical trials, and the number is likely to be much lower in biomedical research."   They also address the possible objection that the "threshold for statistical significance should be different for different research committees."  They say that they agree, and that genetics and high-energy physics have gone for a higher standard--a t-ratio of about 5, but don't even address the possibility that a lower standard might be appropriate.  That is, they seem to take a 10:1 ratio of false to true hypotheses as the minimum, and recommend the .005 standard as a baseline suitable to all fields.  They return to this point in the concluding remarks, where they say that since the .05 level was established "a much larger pool of scientists are now asking a much larger number of questions, possibly with much lower prior odds of success."  This isn't convincing to me.  In the papers I read (published or for review), most of the hypotheses about relations between variables seem pretty plausible.  Even if I don't find the reasoning that leads to the prediction convincing, and often I don't, it's not hard to think of an alternative argument (or several arguments) that leads to the same prediction.  The idea that more scientists asking more questions means lower prior odds of success isn't  compelling either.  In some fields, theory has developed, and that should let you make reasonable predictions on more questions.  In others, there's at least more evidence,  meaning more examples to draw on in making predictions.  So I doubt there is a tendency for the prior odds in favor of proposed hypotheses to decline. 

If they were just making a suggestion about how to interpret the .05 significance level, I would not object, and in fact would generally agree (see my book Hypothesis Testing and Model Selection in the Social Sciences).  But realistically, a "default" of .005 would mean it would become difficult to publish work in which the key parameter estimates were not statistically significant at that level, just as it's now difficult to publish work in which the key parameter estimates aren't significant at the .05 level.*  That would be a loss, not a gain, especially with non-experimental data, where a bigger sample is usually not an option.

*They say results that didn't reach .005 "can still be important and merit publication in leading journals if they address important research questions with rigorous methods,"  but I'm confident that the great majority of reviewers and editors would say that about the .05 level today.  Importance and rigor are matters of judgment, so there's usually disagreement among reviewers; the "default" level of significance is objective, so it takes on outsize importance.

Wednesday, October 11, 2017

Then and now

Ta-Nehisi Coates has a piece called "Civil-Rights Protests Have Never Been Popular," in which he notes that in 1966, 63% of people polled had a negative opinion of Martin Luther King.  The question was asked five times by the Gallup Poll, asking people to rate him on a scale of +5 to -5.  A summary of the results, plus some historical events:

                        +        -        -5
May 1963      41%   37%  (20%)
                                                       March on Washington 8/1963
Aug  1964     44%   38%  (22%)
                                                       Selma march, 3/1965
May  1965     45%  46%   (27%)
                                                        Chicago open housing movement, mid- 1966
Aug   1966    33%  63%   (39%)
Aug   2011    95%    4%    (1%)

During King's life, there was always a significant number giving him the lowest possible rating, which I show in parentheses.

 There are some complications, which I will discuss in the future, but Coates is right in his general point--King was not particularly popular when he was alive, and among whites negative views probably always outnumbered positive views.  Strongly negative views were definitely more common than strongly positive views.

[Data from the Roper Center for Public Opinion Research]

Friday, October 6, 2017

A hypothesis

For some reason that I don't recall, I looked at Edward Banfield's The Unheavenly City Revisited (1974) the other day and ran across this passage, about what he thought was an increasing influence of the middle and upper classes in political life:

"The upper-class ideal . . . requires that issues be settled on their merits, not by logrolling, and that their merits be conceived of in terms of general moral principles that may not, under any circumstances, be compromised.  In the smoke-filled room, it was party loyalty and private interests that mainly moved men; these motives always permitted 'doing business.'  In the talk-filled room, righteous indignation is the main motive, and therefore the longer the talk continues, the clearer it becomes to each side that the other must either be shouted down or knocked down."

Except for the "knocked down," this seems like a good description of the direction of change in American politics since the time he wrote. On the other hand, there is an argument, backed by a good deal of evidence, that increasing levels of education promote stable democracy:  education increases openness to new ideas and ability to see the other person's point of view (see this article for references and more discussion).  So it doesn't seem that Banfield's hypothesis could work as a general rule, but maybe it applies under some circumstances.  One obvious possibility is that the effect of education changes directions--up to a point, increases lead to more willingness to compromise, but beyond that point they reduce it.  There's no systematic evidence of this at the individual level, but it fits with some claims about the politics of intellectuals (see the article referenced above).  Another possibility, which I think is more likely, is that there is some kind of interaction between social conditions and the political system.  That is very vague, but it seems worth thinking about.