Tuesday, 28 February 2017

Reading Creedy

John Creedy is really good at using complicated maths to make simple points. I'll summarise the simple points in Creedy's working paper on sugar taxes, issued earlier this month.

Section 2.1 shows that, whenever people enjoy a bundle of goods of various healthiness, and whenever people are likely to shift from one good to another if prices change, any tax on a particular unhealthy good might reduce consumption of that good while increasing consumption of other less healthy goods. Consequently, you can't just say that a soda tax would improve health - you need to show what the effects are across a broader set of consumption goods. At minimum the you'll get less than you'd hoped for in terms of effects; it's even possible to wind up getting worse health outcomes.

Sections 2.2 and 2.3 work through the maths to get an equation specifying the necessary conditions for a tax on one calorie-heavy food to yield an increase in total calories consumed. That's equation 16.

Walk it through. Food 1 is taxed, Food 2 isn't taxed. An increase in the price of Food 1, presumably through a soda tax, will increase total caloric intake whenever the inequality in Equation 16 holds. It isn't all that likely to hold, but all of these things would also limit the effectiveness of any tax in reducing calorie intake even if we don't get a full reversal from the intended effect.

The first term in the equation is the cross-price elasticity of Food 2 with respect to Food 1. How much does consumption of Food 2 go up if the price of Food 1 increases? So imagine Food 1 is soda with a soda tax and Food 2 is chocolate bars. If the price of soda goes up by 20%*, by how much does consumption of chocolate bars go up? Suppose that chocolate consumption goes up by 5% with a 10% increase in the price of soda. That cross-price elasticity would then be 0.5.

On the other side of the inequality we have another set of terms.

The first of those is the absolute value of soda's own-price elasticity. Why absolute value? Because own-price elasticity is negative (consumption drops when price goes up).

The second is the ratio of the calories in soda as compared to chocolate.

The third is the ratio of budget shares spent on soda as compared to chocolate.

And, finally, the last is the price of chocolate divided by the price of soda.

So what's needed for the soda tax to actually increase calorie intake?

  • The cheaper chocolate is compared to soda, the more likely we get an increase in calorie intake;
  • The more people spend on chocolate as compared to soda at the outset, the more likely that the soda tax has perverse effects;
  • The more calories per unit in chocolate bars as compared to soda, the more likely we are to have perverse effects.
And even if you don't wind up in the case where the soda tax increases calorie intake, you still get less calorie reduction than you'd have expected whenever the three points above are more important. 

I love John's work, but it is pretty tough to read through it unless you know the maths. I don't think he deliberately writes these things to exclude people who can't understand the maths, but it's pretty hard for anybody who doesn't follow the maths to read. 

And so it was ... frankly bizarre ... to read this from the Public Health Blog people:
The Government has an action plan to tackle childhood obesity, but it lacks a tax on sugary drinks – a strategy for which there is good evidence.  A new Treasury Report on soft drink tax price elasticities has just emerged. It has the look of a strategically published document that if and when – during election year – certain politicians need to defend non-action on taxing sugary drinks, they can point to this Report and obfuscate.  Indeed, this New Zealand Treasury Report has already been used for this purpose in Australia. We critique this Report in this blog, with a view to preventing its misrepresentation and to encourage a more informed discussion on taxing sugary drinks. [emphasis added]
If the government wanted to push a strategic anti-sugar-tax report in an election year, it wouldn't have had John Creedy write it. Like, just look at this summary he provides of his illustrative example.

And do note that the text below the graph is about as layperson-friendly as John gets. Does this look like a political document? I wonder what has to be going on in your head if you think that John Creedy is part of some big government conspiracy to write heavily mathy things that maybe one in a thousand people can read.

The public health people then use John's equations to show that it isn't particularly likely that we get an increase in total calorie consumption with a soda tax, but that's not the main point in there. The main point in there is how the effectiveness of any soda tax drops with the combination of things listed in my three bullet point summary.

And as for any alternative theory that would have "Oh, they're writing this up so that people like Crampton can use it in arguing against sugar taxes", well, I didn't even see the point in blogging this piece until they mentioned it. It seemed way too impenetrable even to try blogging about. I'd be a bit surprised if anybody were even still reading this post by now after the maths above.

I did tweet about the report when it came out, mostly because I was exceptionally proud that The Initiative's Jenesa Jeram's work on soda taxes was cited by one of New Zealand's gods of empirical public finance (see footnote 2!).

The other fun bit in the public health people's blog post: they have a big summary of all the not-economists who agree with them about taxes, but continue to ignore Waikato University Professor of Economics John Gibson's work.

But that doesn't mean you have to ignore it. He's giving a talk in Auckland on it that I'd be attending if I were in Auckland. He shows how the estimates of the effects of soda taxes in Mexico are overestimated because consumers shifted to cheaper sodas and, consequently, reduced their soda consumption by maybe a third as much as is often suggested.

And note that John's work on soda taxes is funded through the Royal Society's Marsden Fund, so it's harder for the public health types to simply dismiss on the basis of its funding.

Update: On further thought, it seems a bit odd that Boyd Swinburn is one of the authors on here. The first paragraph implies that John Creedy's work was politically swayed. For a guy who is suing Whaleoil for defamation...

* Note: only an idiot would think that this does not apply to excise just because I used the percent sign and excise is done per unit of whatever rather than in percent terms. Elasticities are just done in terms of percentages. You can turn any excise into a percentage change around different price thresholds to get point elasticities. The effect of any per-unit excise depends on price elasticity. You can probably judge whether somebody gets to count as an economist based on whether they get this. Getting it isn't sufficient for being an economist, but it's necessary.

Harder than it needs to be

The Niskanen Centre shows that immigrants in the United States make less use of government-funded welfare programmes.

It's a nice piece that quickly debunks a lot of popular myths about immigrants.

But it makes me weep how much harder that work is to do here than it is in the USA.

If I want to know, in the US, about whether foreign-born people have higher welfare uptake rates than domestic, all I need to do is go to IPUMS, go to the Current Population Survey, select the variables I want and the years I want extracted, hit the extract request button, and wait for the email saying that the subsample has been extracted for me.

Or, even more easily, I can use their online data analysis tool. And so I did. I'd registered previously with IPUMS. I had to fill in another form to get access to CPS data, which I hadn't used there before. The form auto-populated with the stuff they had on me already. I told them why I wanted the data, then clicked over into the SDA interface for the CPS. Here's what the interface looks like: it's the basic SDA interface Berkeley has that you'll be familiar with from the US GSS - which anybody can use without any login, straight from the website (here you need multi-week approval processes not just to get the data, but for any subsequent use of the data which is different from the purpose which you specified when you got the data in the first place).

If you care about open data, head over to IPUMS to see what is possible. Or even just navigate the SDA interface for the American General Social Survey.

That same work in New Zealand wouldn't be easy. The closest you could get is income source by ethnicity in the 2013 Census publicly available files. I think. Linking that to country of birth would be a specialised data request to Stats, or a trip to the data lab. There is a Confidentialised Unit Record File for the Census - similar to the PUMS available in the US on ACS data. But where anybody with a browser can download the American 5% or 1% samples, you have to make application through the data lab for access to the confidentialised unit record files.

Today StatsNZ put up some new work showing that the wage gap between childless men and women is tiny, while the wage gap between fathers and mothers is larger. It's nice that they've thought to check this, but the damned problem with StatsNZ is that their whole setup requires a stats analyst to think "Ok, maybe people would also be interested in this way of cross-tabulating the data." If you want to know something they haven't added, it's a multi-week application process for access to New Zealand's General Social Survey, for example. And running the HLFS data to adjust for whether the respondent has had a child - that would likely be a trip to the data lab. Meanwhile, American data is just a mouse-click away.

Monday, 27 February 2017

A stupid Newshub beat-up [updated]

Newshub today helped make Kiwis just a little bit stupider. But Ministers not knowing the underlying stats didn't help. [See update below though!]

To recap. The government was put on the spot about whether they're rorting tourism numbers. MSD will sometimes put people in hotels or motels as temporary emergency accommodation. Whether that happens too often relative to an ideal is a different question we'll leave to the side for now. Question at hand is whether that's inflating the tourism numbers. 

Tourism Minister Paula Bennett was asked whether the tourism numbers were wrong because of this. 

The correct answer is "MSD clients are a tiny fraction of overall hotel nights, so it really cannot affect the figures either way." 

Minister Bennett clearly didn't know what's going on in the underlying stats because she said that they aren't included because they're not tourists. Hotels don't know why guests are spending the night. They just report up to Stats how many nights they've provided. [Update - see below] Other non-tourists included in the figures:
  • A couple getting a room for a discreet encounter, who aren't tourists;
  • Someone who realises he is in no shape to drive home and would rather spend the night in the hotel rather than go home drunk in a cab;
  • Someone taking a night at a hotel after a row at home;
  • Someone renting a room as a meeting space;
  • Someone staying in a hotel room during some renovations, or before taking possession of a place they've just bought.
None of it matters. Why? There are almost 22 million domestic guest-nights per year in New Zealand hotels, and over 15 million international guest-nights. How do we know this? The tourism satellite accounts. Here's Table 8.

Neither the international guest nights nor the growth in international guest nights is likely to have been affected at all by MSD clients; they wouldn't have been reported as domestic visitors. It is unlikely that MSD clients have any material effect on the overall domestic guest nights either - it would be like thinking the water volume of Lake Taupo is overstated because nobody netted out the mass of fish in the lake. Yeah, there's fish, but it won't make much difference to the overall figures.

How much effect could it have had? The Newshub story reports 8,860 emergency housing grants in the last quarter of last year at a cost of $7.7 million. Let's say that those are all hotel room nights. Since they're emergency nights, they're not going to be getting "book ahead and save" rates. And they're also potentially riskier for the motellier. Let's say that the room rate is $100 per night but I'd think I'm erring on the low side there. That's (top end) then about 77,000 nights in that quarter. If the room rate is $200/night, then it's 38,500 nights. 

If that had persisted for the whole year, the total number of guest nights would still have rounded to 22 million - but the measured growth rate would have been a bit lower. But, again, would it matter? The government crows about international tourist numbers and guest-nights. Domestic doesn't get noticed as much. 

Prime Minister English noted "if they're counting them as tourists, they shouldn't be." It maybe wouldn't be that hard for MSD to tell Stats how many nights they've purchased and then have those netted from the tourism satellite accounts, but it's stupid hassle for no particularly good reason. And unless they do it all the years back, they're going to break the continuous data definition. 

So, some bottom lines:
  • There is a housing crisis;
  • The government is not fudging the tourism stats by including MSD clients in the tourism satellite accounts, and neither is Stats NZ;
  • It is stupid, and damaging, and unethical, to undermine trust in official statistics in this kind of Gotcha! attack on Ministers who cannot reasonably be expected to know what's in the definition of particular stats - and especially where it is inconceivable that whether or not it is included it would make a whit of difference to the measured tourist night numbers. 
  • I hope that the Statistics Minister, on advice from Stats NZ, would also have told Newshub that the 22 million nights context means that this would just be rounding-error stuff anyway. If he did, and Newshub didn't report that part, that would be worse for them. 
  • If we ever get to the point where MSD emergency grants could materially affect the domestic accommodation guest-night figures, we're going to need a bigger word than crisis to describe what's going on in New Zealand's housing situation.
UPDATE: MBIE's tourism estimates, like the monthly regional tourism estimates, don't use the accommodation survey figures anyway. So if they did use them, it wouldn't matter because the numbers are tiny. But they don't. In this evening's reader mailbag (haven't seen a source link yet):

The Accommodation Survey is produced by Statistics New Zealand monthly to provide information on short-term commercial accommodation activity at a regional and national level. This includes all people staying in commercial accommodation, not only tourists.
Domestic tourism is currently measured by visitor spending, which is not informed by the Accommodation Survey.
MBIE does not use the Accommodation Survey to produce key tourism data products, such as:
  • Monthly Regional Tourism Estimates
  • International Visitor Survey
  • New Zealand Tourism Forecasts.
People with emergency housing grants are not included in these statistics.
However, while it does not inform these products and measures, the Accommodation Survey is part of a suite of statistics that we use to understand the tourism market, both domestic and international. People with emergency housing grants make up a tiny percentage of the approximately 38 million visitor nights recorded annually in the Accommodation Survey.

Wednesday, 22 February 2017

Diversification as insurance: bolthole edition

Idealog asked me last week whether it made sense for billionaires to see New Zealand as a bolt-hole against apocalypse. I had a lot of fun taking a punt at an answer.

New Zealand would do better than other places in some doomsday scenarios, but hardly in all of them.
But Dr Eric Crampton, an economist and the head of research at the New Zealand Initiative, says the billionaires prepping for doomsday may have it wrong.

“For many end-of-the-world scenarios, the best bolthole isn’t the most isolated place in the world, but the wealthiest place in the world,” Crampton says.

“Scenarios leading to collapse in international trade are worse for small countries that are trade dependent than for very large countries that have large internal free-trading areas.”

But he can understand why US citizens would prefer to seek refuge on the other side of the world, particularly in the current political climate.

Crampton is a Canadian that moved to New Zealand from the States in 2003 to take a job at Canterbury University, and he’s stuck around ever since.

“Arriving here, it felt like the outside of the asylum. America was growing increasingly mad. Airports were armed camps. The police seemed to have a very hostile relationship with the public and were heavily armed,” he says.
There's a lot more at the link, including zombies. Enjoy! Bottom line, best billionaire strategy likely has a portfolio of boltholes against a range of potential disasters, and New Zealand could be a nice part of that bundle.

The costs of golf

Auckland Council owned thirteen golf courses as of last year. The NBR talks with Julie Anne Genter and Jacinda Ardern, the two candidates for the Mount Albert by-election, about whether Council should turn the Mount Albert golf course into housing.

I don't know, but strongly suspect, that that land would be of much higher value in housing. Julie Genter is almost certainly correct that the place should be in housing.

But here's how you'd find out.

  1. Zone the land for the highest density of housing that's possible given the infrastructure around the place (or higher, if development could fund upgrading the infrastructure).
  2. Put in an SHA allowing fast development for any future owner. 
  3. Sell the land to the highest bidder, letting the owner keep it as a golf course or develop it.
  4. Tax the land on its market value, whether it's used as a golf course or as housing.
If the golf course can turn a bigger profit from greens fees from paying customers than a developer could earn by turning it into housing, then it should be a golf course. Otherwise, it shouldn't. 

The NBR quotes the golf club's treasurer on that the club currently turns a profit. I wonder what Council charges itself as rent on land that would be worth a fair bit in alternative uses. 

Tuesday, 21 February 2017

Picking zones and picking winners


Earlier this month, the McGuinness Institute argued for what they're calling Demarcation Zones for policy trials. Their formulation differs a bit from what we at the Initiative proposed in 2015, but the core idea is similar: let local communities take on additional devolved powers and see what policy variants seem to work better in which places.

I go through some of the differences in last week's print-edition NBR column. Here's a snippet of the piece:


Dangerous temptations





Friday, 17 February 2017


PredictIt runs a pile of markets on the American Presidency, among other things. Here are some good ones for America-watchers:
The full set of US Politics predictions is here. PredictIt is the US-facing prediction market built by the iPredict team at Victoria University, here in Wellington, to serve American traders. Kiwis cannot trade there. We would have been able to trade on it at iPredict, but we no longer have iPredict.

Thursday, 16 February 2017

More sweet silliness

A new paper suggests strong public health benefits from junk food taxes in Australia. Blogging has been light as I've too much on deck in the day-job currently, but since a few people have emailed me asking about this one, I might as well put here what I've told them.

The effects found in the paper depend on how consumers respond to price increases. Those elasticities are drawn from a 2013 paper estimating elasticities in New Zealand using an Almost Ideal Demand System setup across a couple dozen food categories in household expenditure survey data. But responsiveness of spending to changes in average prices doesn't tell us about consumption if people can shift to cheaper brands within the same category, as John Gibson's Marsden-funded work shows.

And I expect the problem will be worse due to the apparent coarseness of the categories where they’ve aggregated up to 24 total categories: unobserved shifts within broader categories have more potential for problems than within very fine categories. That isn't their fault as likely due to the level of aggregation at which they have average price data, but it would make a mess of things.

If you’re looking at salt intake and the like, and there’s huge variability within the broad categories, that’s going to be a mess. I remember once when Jennie Connor claimed there’d be huge health benefits from alcohol minimum pricing based on some within-alcohol-category elasticity estimates out of BC (own-price elasticity of wine, beer, and spirits, ignoring cross-price elasticities), but increases in wine prices have people shift to beer or spirits; you need to look at aggregate alcohol consumption in response to things like excise changes to get a handle on it (where excise is a de facto minimum price barring implausible loss-leader stuff). So while the paper accounts for cross price elasticities across broad categories, we don't know what's going on to composition mixes within categories.

So they start from overestimated effects of price on quantity consumed. They then go from quantities to dietary intake, although across the broad categories in some cases I’m not sure how they do that (milk, yogurt and eggs is a single category in the 2013 paper; sauces, sugar and condiments is a category; “restaurant food” is a category; “ready to eat” food is a category, though fruit is a single category). Not sure how they estimate change in salt consumption across the categories where the categories are broad and there’s potential for compositional shift within categories.

I also wonder whether the better approach to this stuff might be to look to direct effects rather than chains of dubious link quality? Look at Gelbach, Klick & Stratmann for example. They went directly from prices to obesity and ignored the consumption chains. Andrew Leigh (Top Australian economist, now also Labor MP) blogged on it when he was at ANU.

Finally, I'm not sure that the paper's cost-of-implementation estimate is anywhere close to right. It comes out of estimates on the costs of changes to alcohol excise. But there's an established regime for alcohol excise and the incremental administrative costs of changes within that won't be large. Plus that’s just administrative cost – zero consideration I can see of forgone consumer surplus. Like, even if you’re balancing it out with healthy food subsidies, there’s a reason people are choosing to eat the tastier things currently.

Caveat: this is just a quick take on the paper. If others have caught problems that I've missed, or if I've misread them, please let me know in comments.

Friday, 10 February 2017

Dumb corporate welfare

Citizenship for Peter Thiel made a lot of sense. I laid out the case over at the Spinoff. 

Corporate welfare is different.

Matt Nippert asked me last week for comment on the government's venture capital fund, which wound up partnering with Thiel in some of his New Zealand investment. The government's fund effectively lets government share in downside risk but not upside.

Eric Crampton, economist and head of research for pro-market think-tank NZI, had previously defended the government's granting of citizenship to Thiel who gained approval after appealing to then-Internal Affairs Minister Nathan Guy to waive requirements he live or intend to live here due to "exceptional circumstances".
Crampton said that decision was a "bet worth making at the time, and one that should not be regretted in retrospect".

However, following revelations Thiel exercised a buyout option in his partnership with the publicly-funded New Zealand Venture Investment Fund - a move that netted the Paypal founder $24m in profits while leaving NZVIF barely breaking even despite both parties bearing equal risk of loss - Crampton said going into business with Thiel was a gamble the Government should not have taken.

"The Government should not be involved in investment pump-priming activities," he said.

"Government economic diversification schemes, in which the government shares in the downside risk if the investment turns sour but only benefits on the upside through increased tax revenues from a successful business, are adventures best avoided," Crampton said.
The government just shouldn't be in this kind of business.
Finance Minister Steven Joyce, whose previous tenure as Minister of Economic development covered the NZVIF during the entire period of the funds' operation and buyout, yesterday continued to blame Labour for Thiel's multi-million dollar payday.
The partnership between NZVIF and Valar was announced by Joyce in 2012 and bought out by Thiel last October. But Joyce said the buyout option had been a feature of the NZVIF's formation in 2002 by the fifth Labour Government until he had requested it cease being used in 2015.
"We've subsequently changed it, but it was done by the government at the time and it worked exactly as they intended it to," Joyce said.
Labour Party's immigration spokesman Iain Lees Galloway has previously labelled the arrangement a "sweetheart deal" for Thiel overseen by Joyce.
Crampton called on the political finger-pointing to end.
"It would be nice if National and Labour stopped trying to blame each other for this particular deal and instead came to common agreement on ending corporate welfare," he said.
It's also been written up at the Straits Times. I talked with Radio NZ's Panel about it.

Meanwhile, Canada throws money at airplanes....

We can detain them for you, wholesale.

Recent adventures in America remind me of Neil Gaiman's excellent "We can get them for you, wholesale."

I'm going to give a big spoiler here. Go away and read the whole thing, then come back. Or read the spoiler and then go away and read the whole thing anyway. Or watch this film version.

Spoiler ahead.

Here it comes...

Ok, you've been warned.

The protagonist in that story is in search of a contract killer. He finds one under Pest Control in the Yellow Pages. And he finds that they're more than happy to do the job, in bulk, at a discount. The bigger the numbers the lower the total price. A bargain is a bargain. And then he starts wondering about even bigger bulk deals:
"How much would it cost to kill everybody? Everybody in the world?"

"Everybody? All the people?

"Yes. How much? I mean, for an order like that, you'd have to have some kind of a big discount. How much would it be? For everyone?"

"Nothing at all, Mr Pinter."

"You mean you wouldn't do it?"

"I mean we'd do it for nothing Mr Pinter. We only have to be asked you see. We always have to be asked."

Peter was puzzled. "But - when would you start?"

"Start? Right away. Now. We've been ready for a long time. But we had to be asked, Mr Pinter. Good night. It has been a pleasure doing business with you."
I feel kind the same way about how US customs agents have been treating people under the cover of the President's executive order. They've always wanted to do that. They've been ready for a long time. They only had to be asked.
I've been saying it for rather a while here, but emigration to New Zealand can be an option.

And thanks to Lyndon Hood for reminding me that the story was Gaiman's.

Thursday, 2 February 2017

Doing the right thing, and doing well as consequence.

My piece in Monday's Dom Post:
In the immediate term, there are uncounted thousands of legal American residents who are not able to return home if they are currently outside America, or who risk not being able to return if they leave America. They passed through some of the world's most rigorous scrutiny before being granted refugee status, work visas, or permanent residence. And they are now disadvantaged because of the country of their birth.

America has long been a magnet for the world's most talented people. And America's most advanced industries rely heavily on foreigners allowed to work in the United States on H1-B visas. America's universities are the best in the world because they attract top scholars from everywhere. Foreigners on H1-B visas or with permanent residence teach foreign students on F visas, making education a massively successful American export industry.

New Zealand should announce a new visa category for people who were legally entitled to live and work in America until the Executive Order broke things. If the New Zealand government has wanted to attract more highly skilled migrants, there would be few better bets than trying to help those who have been hurt by American policy.
Expand the trial of the Canadian-style refugee sponsorship regime to accommodate those with whom America has broken faith - in as large of quantities as Kiwis are prepared to support through their private sponsorship efforts. I don't know what the right number is, but I do know that if Kiwis get together to cover the refugee's transitional costs, the government should not be in their darned way.

And opening up a new skilled migrant category that would simply give a visa to anybody in the States on an H1-B would be pretty simple. You can't even get an H1-B in the States if you're not earning at least $60k - this wouldn't be an influx of low-skilled people that agitates everybody. If the only way to make it work politically is to put in an entry levy to defray perceived infrastructure costs, so be it. They'd all be eligible for our current skilled migrant visas anyway, or just about all of them. There are hassles there where you need the points from a job-in-hand to get the visa, and some Kiwi employers haven't quite wrapped their heads around that making the job offer means the visa is pretty simple afterwards.

Meanwhile, Silicon Valley looks to move its foreign-born workers to Canada. Canada was always going to be at an advantage due to time zones and proximity. But it helped that the Canadian Prime Minister took a very welcoming approach to those hurt by Trump. New Zealand didn't, and we are missing an opportunity to help people while also improving the country's skilled migrant base.

I concluded:
Those who New Zealand might help would likely return to America when it returns to its senses. But some of those temporarily displaced could become excellent new New Zealanders.

This week, the New Zealand Initiative released The New New Zealanders: Why migrants make good Kiwis. It provides a stocktake on immigration to New Zealand, finding that migrants make a substantial contribution, and that many of the fears around immigration are not supported by the data.

Any migrants New Zealand did attract from America would be especially likely to contribute to New Zealand's skill base. But doing well in this way should be seen as a side-effect of doing good rather than the reason for doing it. New Zealand should help because we can, because it is the right thing to do, and because it shows our support for our friends in America during a difficult time.
Our report notes that migrants to New Zealand already more than pay their way in net taxes. But if concerns over infrastructure costs are critical, we could do better by using a levy on new migrants than by cutting their numbers: it could sustain a political equilibrium allowing more migration than otherwise. I really don't like the idea of the levy, because migrants are already paying their way on average.

But if your reason for opposing immigration and cutting numbers is infrastructure costs, you should support a levy instead of supporting cutting the numbers. If you argue for cutting the numbers instead of a levy, and you claim it's because of infrastructure costs or other costs that could be easily mitigated with a levy, I kinda don't believe your stated reasons for opposing immigration. And there are sometimes darker, unstated reasons for opposing immigration.

Update: Vox on Trump on visa holders.