Bob Shiller's Nobel

As with Lars Hansen and Gene Fama, Bob Shiller has also produced a span of interesting innovative work, that I can't possibly cover here. Again, don't let a Nobel Prize for one contribution overshadow the rest. In addition to volatility, Bob did (with Grossman and Melino) some of the best and earliest work on the consumption model, and his work on real estate and innovative markets is justly famous.  But, space is limited so again I'll just focus on volatility and predictability of returns which is at the core of the Nobel.

Source: American Economic Review

The graph on the left comes from Bob's June 1981  American Economic Review paper. Here Bob contrasts the actual stock price p with the "ex-post rational" price p*, which is the discounted sum of actual dividends. If price is the expected discounted value of dividends, then price should vary less than the actual discounted value of ex-post dividends.  Yet the actual price varies tremendously more than this ex-post discounted value.

This was a bombshell. It said to those of us watching at the time (I was just starting graduate school) that you Chicago guys are missing the boat. Sure, you can't forecast stock returns. But look at the wild fluctuations in prices! That can't possibly be efficient. It looks like a whole new category of test, an elephant in the room that the Fama crew somehow overlooked running little regressions.  It looks like prices are incorporating information -- and then a whole lot more!  Shiller interpreted it as psychological and social dynamics, waves of optimisim and pessimism.

Lars Hansen's Nobel

Lars has done so much  deep and pathbreaking research, that I can't begin to even list it, to say nothing of explain the small part of it that I understand.  I wrote whole chapters of my textbook "Asset Pricing" devoted to just one Hansen paper. Lars writes for the ages, and it often takes 10 years or more for the rest of us to understand what he has done and how important it is.

So I will just try to explain GMM and the consumption estimates, the work most prominently featured in the Nobel citation. Like all of Lars' work, it looks complex at the outset, but once you see what he did, it is actually brilliant in its simplicity.

The GMM approach basically says, anything you want to do in statistical analysis or econometrics can be written as taking an average.

Understanding Asset Prices

The Nobel Committee's "Understanding Asset Prices" "scientific background" paper for the Fama, Hansen, Shiller award is excellent. It is pretty much a self-contained graduate course in empirical finance.

Gene Fama's Nobel

(For a pdf version click here.)

Photo: Elizabeth Fama

Gene Fama’s Nobel Prize

Efficient Markets

Gene’s first really famous contributions came in the late 1960s and early 1970s under the general theme of “efficient markets.” “Efficient Capital Markets: a Review of Theory and Empirical Work’’ [15] is often cited as the central paper. (Numbers refer to Gene’s CV.)

“Efficiency” is not a pleasant adjective or a buzzword. Gene gave it a precise, testable meaning. Gene realized that financial markets are, at heart, markets for information. Markets are “informationally efficient” if market prices today summarize all available information about future values. Informational efficiency is a natural consequence of competition, relatively free entry, and low costs of information in financial markets. If there is a signal, not now incorporated in market prices, that future values will be high, competitive traders will buy on that signal. In doing so, they bid the price up, until the price fully reflects the available information.

Like all good theories, this idea sounds simple in such an overly simplified form. The greatness of Fama’s contribution does not lie in a complex “theory” (though the theory is, in fact, quite subtle and in itself a remarkable achievement.) Rather “efficient markets” became the organizing principle for 30 years of empirical work in financial economics. That empirical work taught us much about the world, and in turn affected the world deeply.

For example, a natural implication of market efficiency is that simple trading rules should not work, e.g. “buy when the market went up yesterday.” This is a testable proposition, and an army of financial economists (including Gene, [4], [5],[ 6]) checked it. The interesting empirical result is that trading rules, technical systems, market newsletters and so on have essentially no power beyond that of luck to forecast stock prices. It’s not a theorem, an axiom, or a philosophy, it’s an empirical prediction that could easily have come out the other way, and sometimes did.

Fama, Hansen, and Shiller Nobel

Gene Fama, Lars Hansen and Bob Shiller win the Nobel Prize. Congratulations! (Minor complaint: Nobel committee, haven't you heard of Google? There are lots of nice Gene Fama photographs lying around. What's with the bad cartoon?)

I'll write more about each in the coming days. I've spent most of my professional life following in their footsteps, so at least I think I understand what they did more than for the typical prize.

As a start, here is an an introduction I wrote for  Gene Fama’s Talk, “The History of the Theory and Evidence on the Efficient Markets Hypothesis” given for the AFA history project. There is a link to this document on my webpage here. The video version is here at IGM.

Introduction for Gene Fama

On behalf of the American Finance Association and the University of Chicago Graduate School of Business, it is an honor and a pleasure to introduce Gene Fama. This talk is being videotaped for the AFA history project, so we speak for the ages.

Gene will tell us how the efficient-markets hypothesis developed. I’d like to say a few words about why it’s so important. This may not be obvious to young people in the audience, and Gene will be too modest to say much about it.

“Market efficiency” means that asset prices incorporate available information about values. It does not mean that orders are “efficiently” processed, that prices “efficiently” allocate resources, or any of the other nice meanings of “efficiency.” Why should prices reflect information? Because of competition and free entry. If we could easily predict that stock prices will rise tomorrow, we would all try to buy today. Prices would rise today until they reflect our information.

Friday Art Fun

Totally off topic. It's Friday, time to relax.

Source: Nina Katchadourian

15th Century Flemish Style Portraits Recreated In Airplane Lavatory Click the link for the full set.

From the artist:

While in the lavatory on a domestic flight in March 2010, I spontaneously put a tissue paper toilet cover seat cover over my head and took a picture in the mirror using my cellphone. The image evoked 15th-century Flemish portraiture. <…> I made several forays to the bathroom from my aisle seat, and by the time we landed I had a large group of new photographs entitled Lavatory Self-Portraits in the Flemish Style

From the art critic (Sally Cochrane)

What no one's saying, though, is that she was hogging the bathroom while a line of antsy people held their bladders! 

In related art news, the street artist Banksy is prowling New York. A group of Brooklyn locals, seeing people coming in to photograph the stencil, promptly covered it with cardboard and starting charging $5 per shot. Entrepreneurship and property rights are still alive.

Krugtron parts 2 and 3

Niall Ferguson has completed his Krugtron trilogy, with Part 2 and Part 3, (Part 1 here FYI, which I blogged about earlier.)

Part 2 continues Part 1. In fact, Krugman is as human as the rest of us, and the future is hard to see. Niall compiles a long record of what Krugman actually said at the time. As before, those of us on the sharp end of Krugman's insults enjoy seeing at least his own record set straight.

But Niall admits what I said last time: we don't really learn much from anyone's prognostication

In the past few days, I have pointed out that he has no right at all to castigate me or anyone else for real or imagined mistakes of prognostication. But the fact that Paul Krugman is often wrong is not the most important thing. ..

What Niall is really mad at are the insults, the lying and slandering (I'm sorry, that's what it is and there are no polite words for impolite behavior), and the lack of scholarship -- Krugman does not read the things he castigates people for.

And it matters.

Mulligan on Obamacare Marginal Tax Rates

Casey Mulligan wrote a nice Wall Street Journal Oped last week, summarizing his recent NBER Working Paper (also here on Casey's webpage) on marginal tax rates.

What do I mean, tax, you might ask. Obamacare is about giving people stuff, not taxing. Sadly, no. Obamacare gives subsidies that are dependent on income. As you earn more, you receive fewer subsidies for health care, reducing the incentive to earn more. Casey tots this sort of thing up, along with the actual taxes people will pay.

Economists use the word "tax" here and we know what we mean, but it would be better to call it "disincentives" so it's clearer what the problem is, and just how painful we make it for poor people in this country to rise out of that poverty.

As you can see, the average marginal "tax" rate went up 10 percentage points since 2007, and about 5 percentage points due to Obamacare alone.

Going back to the working paper, I think this is actually an understatement. (Probably the first time Casey or I have ever been accused of that!)

Margins on Exchanges

A nice Bloomberg View by David Goldhill offers an Econ 101 lesson in incentives. Though the average subsidy rate to health insurance is limited, the marginal subsidy rate is 100% once consumers hit the income limits -- so many consumers have no incentive at all to shop for lower prices. In turn, this greatly lowers the chance that insurers will compete on price.

David:

Let’s take an example. A family of four at 138 percent of the poverty level ($32,499) has its premium capped at 3.29 percent of income or $1,071. The rest is subsidy. So, if the cost of a silver plan is $10,000, the subsidy for this family is $8,929. A family at 400 percent of the poverty level ($94,200) has to pay up to 9.5 percent of its income for a plan, or $8,949. So the same $10,000 premium carries a subsidy of only $1,051.

But now look at those two families from the insurer’s perspective. A $10,000 plan already costs more than the maximum amount either family would pay. If the insurer raises the premium to $10,001, both families get $1 in additional subsidy. If it raises premiums to $11,000, both families get $1,000 in additional subsidy. In other words, no matter how much an insurer raises rates, a subsidized household pays zero more.

Ferguson on Krugtron

A fun show is breaking out. Niall Ferguson on "Krugtron the invincible."

Paul Krugman, for a while now, has been lambasting those he disagrees with by trumpeting their supposed "predictions" which came out wrong, and using words like "knaves and fools" to describe them -- when he's feeling polite. These claims often are based on a rather superficial, if any, study of what the people involved actually wrote, mirroring the sudden narcolepsy of Times fact-checkers any time Krugman steps in to the room. Niall has lately been a particular target of this calumnious campaign.

Niall's fighting back. "Oh yeah? Let's see how your "predictions" worked out!" Don't mess with a historian. He knows how to check the facts. This is only "part 1!" Ken Rogoff seems to be on a similar tear. (and a new item here.) This will be worth watching.

Dupor and Li on the Missing Inflation in the New-Keynesian Stimulus

Bill Dupor and Rong Li have a very nice new paper on fiscal stimulus: "The 2009 Recovery Act and the Expected Inflation Channel of Government Spending" available here.

New-Keynesian models are really utterly different from Old-Keynesian stories. In the old-Keynesian account, more government spending raises income directly (Y=C+I+G); income Y then raises consumption, so you get a second round of income increases.

New-Keynesian models act entirely through the real interest rate.  Higher government spending means more inflation. More inflation reduces real interest rates when the nominal rate is stuck at zero, or when the Fed chooses not to respond with higher nominal rates. A higher real interest rate depresses consumption and output today relative to the future, when they are expected to return to trend. Making the economy deliberately more inefficient also raises inflation, lowers the real rate and stimulates output today. (Bill and Rong's introduction gives a better explanation, recommended.)

So, the key proposition of new-Keynesian multipliers is that they work by increasing expected inflation. Bill and Rong look at that mechanism: did the ARRA stimulus in 2009 increase inflation or expected inflation?  Their answer: No.

Eight young stars

Eight of the World’s Top Young Economists Discuss Where Their Field Is Going is a interesting post, interviewing a few of economics' young stars. It's about a year old, but a correspondent just sent it to me and I think it's still good reading.

It's particularly good reading for PhD students. These are better models to emulate than older economists, as they tell you a bit more what directions are going well now -- at least what gets you baptized a star! Here are a few things I noticed.

Rogoff on UK Defaults

Ken Rogoff wrote a very interesting FT oped on UK finances (FT original, Rogoff webpage if you can't see FT.)

The issue: Should we worry about huge sovereign debts of advanced countries? Or was the only problem with fiscal stimulus that it was not big enough?

Financial Reform in 12 Minutes

I was on a panel yesterday at a fascinating conference, "The US Financial System–Five Years after the Crisis."  The conference was run simultaneously at Hooover and Brookings, with a live video link. Which went dead exactly as I was proclaiming the wonders of modern technology, but otherwise worked remarkably well. Alas, the conference was run under "Chatham house rules" so I can't tell you all the remarkable things that the Very Important People said. I can pass on surprise that there was so little disagreement between the Brookings and Hoover sides. I was expecting a spirited defense of Dodd-Frank from the East. Instead, they piled on it, if anything more eloquently that the West, with only one very thoughtful but still lukewarm defense.  I hope the presentations will eventually be made public, as they were uniformly interesting -- even the ones I disagreed with I thought were wrong in very interesting and thoughtful ways.

I was given 12 minutes to comment on the state of financial reform, is too big to fail over, are we ready for the next crisis. My answer follows. Yes, faithful readers will recognize something of a moving average, which will continue both to move and to average.

Have fun

Financial Reform in 12 Minutes

Is too big to fail over? No. Are we ready for the next crisis? Absolutely not. 

Miron and Rigol go after a classic

Jeff Miron and Natalia Rigol have a provocative working paper, "Bank Failures and Output During the Great Depression." They take on one of Ben Bernanke's most famous papers.

Is QE contractionary?

I ran across a fascinating blog post by Peter Stella at Vox-Eu on exit strategies and QE. 

Peter points out that only banks can hold reserves, while anyone can hold short term Treasuries. And you can easily use Treasuries for collateral.  That means that short term Treasuries are in some sense more liquid than reserves, and that by buying huge amounts of Treasuries and issuing reserves, the Fed may be actually contracting. 

Asset Pricing MOOC Open

My Coursera Asset Pricing MOOC is now open. The direct link is here -- but you may need to register to see it. 

I recommend browsing the week 1 videos, especially the theory preview videos, if you want a sense of what it's all about. Week 0 is background material on continuous time math.

Week 0 (background) and week 1 are up now, 2 and 3 should be up later this week.

Warning, this is a PhD level asset pricing class, designed to get you in to the theory used for research-level asset pricing. It pretty much follows my textbook "Asset Pricing" (and supplementary material) You don't have to buy the text to take the Coursera class. People who just want to watch the videos are also welcome.

The New-Keynesian Liquidity Trap

I just finished a draft of an academic article, "The New-Keynesian Liquidity Trap"  that might be of interest to blog readers, especially those of you who follow the stimulus wars. 

New-Keynesian models produce some stunning predictions of what happens in a "liquidity trap" when interest rates are stuck at zero.  They predict a deep recession. They predict that promises work: "forward guidance," and commitments to keep interest rates low for long periods, with no current action, stimulate the current level of consumption.  Fully-expected future inflation is a good thing. Growth is bad. Deliberate destruction of output, capital, and productivity raise GDP. Throw away the bulldozers, let them use shovels. Or, better, spoons. Hurricanes are good. Government spending, even if financed by current taxation, and even if completely wasted, of the digging ditches and filling them up type, can have huge output multipliers.

Even more puzzling, new-Keynesian models predict that all of this gets worse as prices become more flexible.  Thus, although price stickiness is the central friction keeping the economy from achieving its optimal output, policies that reduce price stickiness would make matters worse.

In short, every law of economics seems to change sign at the zero bound. If gravity itself changed sign and we all started floating away, it would be no less surprising.

And of course, if you read the New York Times, people like me who have any doubts about all this are morons, evil, corrupt, and paid off by some vast right-wing conspiracy to transfer wealth from the poor to the secret conspiracy of hedge fund billionaires.

So I spent some time looking at all this.

McDonalds and the minimum wage

Recently, on a long car trip returning from a glider contest, I did something unusual among our liberal elite: I actually went to a McDonalds and ate there.

The lady who took my order must have been about 19, as were all the other employees I could see, and pretty clearly new on the job.  Getting the order right took some effort.  I made the mistake of paying cash. The bill was something like $7.62. I first offered a $10, and she rang it up. Then I found 12 cents in my pocket, and offered it. This was a big mistake, as the cash register had already computed my change, and adjusting to my offer of 12 cents was beyond her abilities.

Most people might have been annoyed, but as an economist and an educator, I'm happy to see human capital building. OK, I was a little annoyed.

Which brings me, of course, to the proposals for a sharply increased minimum wage.

Summers withdraws

You have undoubtedly seen the news by now. Chicago Tribune, and Wall Street Journal

I'm sad, actually. A Summers confirmation would have been a great focus for a national debate on the role of the Federal Reserve, the role and character of its Chair, proper relations between the Fed and Wall Street, where we are going with financial regulation, whether bailouts and stimulus are a good idea, and how macroeconomic and monetary policy should be conducted.

I mean that as a totally honest statement -- don't read any coded pro- or anti- Summers implications in it.

I don't see that happening with any of the remaining candidates. We are at a good moment to attract some lightning, and I'm sorry to see the lightning rod bow out.