Come Work With Me: UMN APEC Is Hiring in Environmental and Resource Economics

A little over a year ago, I was fortunate to move to a department where my colleagues were all trained in the same discipline and methods I was trained in.

A department where, because I don’t have to spend the better part of my time justifying why my research is interesting, I can focus on doing more and better research, and where I can have a fulfilling career.

And last, but not least, a department where the atmosphere is also eminently collegial, relative to many other places.

If you are an environmental or natural resource economist and the foregoing sounds like a place where you can see yourself, we are hiring at the assistant professor level in that broad area. Here is our advertisement, from the latest round of Job Openings for Economists: Continue reading

Mean ≠ Variance*

A lot of my research has been driven by the fact that the mean of the distribution and the variance of the distribution usually have different impacts on welfare; see this and that, for example.

Imagine that your income next year is going to be a random number of dollars in the $30,000 to $120,000 interval, a scenario that isn’t completely crazy if you are, say, a farmer in a middle-income country.

Assuming your welfare increases with income, an increase in the mean of your random income is a good thing. In other words, holding the [$30,000, $120,000] interval constant, you would prefer your expected income to be equal $90,000 rather than $60,000.

Alternatively, whether you prefer a more variable income or not depends on your risk preferences. So holding constant both the [$30,000, $120,000] interval as well as your expected income of $90,000, an increase in the variance of your income might affect you differently than it would someone else. If your income is normally distributed with a standard deviation of $5,000, then in about 19 out of 20 cases, your income will lie in the [$80,000, $100,000] interval. If your income is normally distributed with a standard deviation of $10,000, then in about 19 out of 20 cases, your income will lie in the [$70,000, $110,000] interval. So which do you prefer: A $5,000 standard deviation, or a $10,000 standard deviation?

There is no right answer, as what’s right for you depends on your risk preferences. A risk-neutral individual will be indifferent between the two. A risk-averse individual will prefer a $5,000 standard deviation to the $10,000 deviation (and, to the extent that it is feasible, they would prefer a $0 standard deviation, which is why crop insurance is hugely popular among farmers!) A risk-loving individual will prefer the $10,000 standard deviation.

Sounds sensible, doesn’t it? Except it often happens that people have a hard time thinking through the difference between the mean and variance of a distribution. This is especially true for college students who, by virtue of being more educated than the vast majority of the population, really should know better:

Imagine two course sections with the following grading schemes:

Section A: 4 assignments worth 5% each for a total of 20%; 35% midterm; 45% final.

Section B: 4 assignments worth 10% each for a total of 40%; 60% final.

In my experience, students often reason: “Section B places more weight on assignments. I can work with my friends and use other resources, and get good marks on the assignments. Therefore it’ll be easier to get a good grade in Section B.”

But professors know students work together on assignments, and it’s almost impossible to tell who has done the work and who has just copied it. They put weight on the assignments, so that students have an incentive to complete them. But profs don’t want the assignments to have much influence on the students’ final grade.

The best way to diminish the effective influence of assignments is to give everyone more or less the same grade – say 80 percent. That way assignments just scale up the class average, and students’ relative position in the class is primarily determined by their score in the examinations.

That is from a longer post by Frances Woolley over at the Worthwhile Canadian Initiative blog, about how students often completely miss the obvious fact that what matters is not so much their absolute score, but where they rank relative to the mean, or as I once heard someone say in college: “It doesn’t matter that you be good at this, all that matters is that you be better than most others at it.”

I remember all of the students in a course I was teaching four or five years ago failing to answer one of the questions on a midterm. That question, I think was worth 5 points. When I told the students that I had given everyone five additional, “bonus” points because that question had proved too difficult, a number of students thought that this was really, really great news.

But those students should really have known better, however, since I had already told them that I would curve the grades and the mean would be a B+. Those 5 free points on that midterm merely gave them the illusion that they were doing better, since it only moved the distribution a bit to the right, without changing the variance or the rank-ordering of students.

* Except for a Poisson distribution, that is.

What Would an African Green Revolution Entail for Land Use and CO2 Emissions?

Wheat in Israel. (Source: Wikimedia Commons.)

Most of the readers of this blog are familiar with the Green Revolution which, according to Wikipedia,

refers to a series of research, and development, and technology transfer initiatives, occurring between the 1940s and the late 1960s, that increased agricultural production worldwide, particularly in the developing world, beginning most markedly in the late 1960s.

The name most often associated with the Green Revolution is that of Norman Borlaug. Borlaug was a plant scientist and University of Minnesota alumnus whose work on plant breeding led to the maize yield improvements that paved the way for greater food security since the 1970s. Borlaug also won the Nobel peace prize for his work.

The innovations brought forth by the Green Revolution worked really well in Asia and, to a lesser extent, in Latin America (in his book Food Politics, Rob Paarlberg has a good discussion of the institutional differences that led to different outcomes). The Green Revolution, however, has almost completely bypassed Africa (with the result that African yields have either stagnated or decreased over the last few decades), so a lot of the discussion surrounding food policy debates in recent years has focused on how an African Green Revolution can happen, and what it will look like. Continue reading

On Small vs. Large Farms: Yours Truly in the Washington Post

Small, diversified farms are less efficient than large ones. Which means that food grown on them is more expensive. Marc Bellemare, an assistant professor in the University of Minnesota’s department of applied economics, calls farmers market produce “luxury goods,” and Tim Griffin, director of the Agriculture, Food and Environment program at Tufts University’s Friedman School of Nutrition Science and Policy, explains the dynamic simply: economy of scale. “As the farms get larger, it’s easier to invest in labor-saving machinery, technology and specialized management, and production cost per unit goes down,” he says. It’s Econ 101.

Even John Ikerd, professor emeritus of agriculture and applied economics at the University of Missouri and an outspoken advocate of the idea that small organic farms ought to feed the world — an idea Bellemare calls “wishful thinking” — acknowledges that we’d need many more farmers to make that happen, and that food would be more expensive.

From an article in the Washington Post last week.

In the middle of July, I received an email from Tamar Haspel, who writes the Unearthed column about food for the Washington Post, and who is herself a farmer (she farms oysters on the coast of Massachusetts). She wanted to talk about the inverse relationship between farm size and productivity, which I have written about both on this blog and in a 2010 article in World Development. The end result is the article I link to above.

Why Are We Importing Our Own Fish? Because It is Efficient to Do So (and a New Working Paper)

From an op-ed published this summer in the New York Times:

Sending all this wild fish abroad and then importing farmed fish to replace it is enough to make you want to take a stiff drink and go to bed. But when you wake up and reach for your bagel, surprise! The fish swap will get you again.

The United States imports seafood in increasing numbers, even for salmon, which it has in abundance.

The prevalence of imported farmed salmon on our bagels is doubly curious because the United States possesses all the wild salmon it could possibly need. Five species of Pacific salmon return to Alaskan rivers every year, generating several hundred million pounds of fish flesh every year. Where does it all go?

Again, abroad. Increasingly to Asia. Alaska, by far our biggest fish-producing state, exports around three-quarters of its salmon.

To make things triply strange, a portion of that salmon, after heading across the Pacific, returns to us: Because foreign labor is so cheap, many Alaskan salmon are caught in American waters, frozen, defrosted in Asia, filleted and boned, refrozen and sent back to us. Pollock also make this Asian round trip, as do squid — and who knows what else?

When you dig into the fish-trade data, things get murkier. In its 2012 summary of the international fish trade, the National Oceanic and Atmospheric Administration noted, somewhat bizarrely, that its definition of exports “may include merchandise of both domestic and foreign origin.”

So, for example, when fish sticks are cut from blocks of imported “white fish” in an American facility and exported to a foreign country, they are classified as American domestic production. Meanwhile some of our imports, as with an unknowable portion of our salmon, are taken from American waters, reprocessed elsewhere and brought back home. …

And that’s my point. Globalization, that unseen force that supposedly eliminates inefficiencies through the magic of trade, has radically disconnected us from our seafood supply.

Continue reading