Thread by @Noahpinion

1/A quick thread about this number. It's made up. But how many people are really in the country illegally?

https://twitter.com/jeffmason1/status/1080522379846213634

2/The typical number for unauthorized immigrant residents is around 11 million. This is based on surveys, meaning you go around asking whether they're foreign-born, then subtract the # of legal immigrants from the total.
pewresearch.org/fact-tank/2018…

3/But of course people might refuse to answer the survey if they thought it could get them in trouble (it can't...yet).

So some folks at Yale tried to estimate the total # of unauthorized residents using data on inflows and outflows.

journals.plos.org/plosone/articl…

4/There are LOTS of assumptions required for this approach - what percent of border-crossers get apprehended, how many people move back, etc. So there's a huge margin of error.

5/The Yale study's average estimate for the number of unauthorized residents is 22 million. Their 95% confidence interval is 16.2 to 29.5 million.

BUT, assuming a slightly smaller inflow in the 90s changes that interval from 13.5 million to 21.1 million. So it's very sensitive.

6/If you set all of their assumptions to maximum, you can get around 35 million, which is where Trump probably got his number (maybe from Miller reading the study and quoting that number to him?). But this is highly unrealistic.

7/Now the Yale study does have some problems, as detailed in this Cato report: cato.org/blog/what-ther…

One of the biggest problems: Mexican survey data show a LOT more people moving back to Mexico in the 90s. Using Mexican data on return migration destroys the Yale result.

8/Another problem is that birth records, school records, and death records make it very difficult for unauthorized immigrants to hide their existence totally. And according to Cato, these records don't indicate a hidden unauthorized population of >11 million people.

9/So the total unauthorized population *might* be substantially higher than the commonly cited 11 million number, but maybe not.

And the numbers Trump is quoting are just totally wrong and impossible.

10/One more note. Both the Yale study AND the commonly cited survey-based measures agree that the number of unauthorized residents has been falling steadily since around 2007. In fact, the Yale study finds a slightly larger decrease since then.

11/So not only is Trump massively overstating the number of people living here illegally, he's neglecting the fact that the number has been falling for a decade.

The illegal immigration issue really ended a decade ago, and now we're just fighting over the aftermath.

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