The first randomized controlled trial of police body cameras shows that cameras sharply reduce the use of force by police and the number of citizen complaints.

We conducted a randomized controlled trial, where nearly 1,000 officer shifts were randomized
over a 12-month period to treatment and control conditions. During ‘‘treatment shifts’’
officers were required to wear and use body-worn-cameras when interacting with members
of the public, while during ‘‘control shifts’’ officers were instructed not to carry or use the
devices in any way. We observed the number of complaints, incidents of use-of-force, and
the number of contacts between police officers and the public, in the years and months
preceding the trial (in order to establish a baseline) and during the 12 months of the

The results were that police use of force reports halved on shifts when police wore cameras. In addition, the use of force during the entire treatment period (on shifts both using and not using cameras) was about half the rate as during pre-treatment periods. In other words, the camera wearing shifts appear to have caused police to change their behavior on all shifts in a way that reduced the use of force. A treatment that bleeds over to the control group is bad for experimental design but suggests that the effect was powerful in changing the norms of interaction. (By the way, the authors say that they can’t be certain whether the cameras primarily influenced the police or the citizens but the fact that the effect occurred even on non-camera shifts suggests that the effect is primarily driven by police behavior since the citizens would not have been particularly aware of the experiment, especially as there would have been relatively few repeat interactions for citizens.)

It is possible that the police shaded their reports down during the treatment period but complaints by citizens also fell dramatically during the treatment period from about 25-50 per year to just 3 per year.

Here’s a graph of use of force reports before and during the treatment period.


Police cameras will have some negative effects. When a police officer is accused of something will lawyers have the right to subpoena years of camera footage looking for anything problematic? Think about the OJ case. Perhaps tape should be erased after one year.

Nevertheless, the results of the study are impressive. More generally, I worry that there is no solution to the problem of government mass surveillance but at the very least we can turn the cameras around and even the playing field.

Poker markets in everything

by on January 13, 2015 at 2:23 am in Economics, Food and Drink, Games | Permalink

All-In Kitchen, which will be opening in Haggerston, London, will see diners’ success at the poker table determine how much they pay for their meal.

There is more here, via Mark Thorson.  And here are some Chinese cars with guppy tanks.

In response to my earlier post, Kevin Drum attempts to identify the problem of austerity by graphing real, per capita government spending in the United States.  But choosing real government spending can be a misleading way of measuring the contribution of fiscal policy to aggregate demand.  (The per capita decision also can be partially disputed on the grounds that government is producing some national public goods.)

Real cuts in government spending, when due to inflationary erosion of G, will not in general be identifying a problem of aggregate demand.  And aggregate demand is what we are considering here, not potential problems with supply provision (e.g., how many children are getting vaccines?), which are well identified by looking at the real variables.

Take two societies, each with flat nominal government spending.  One society has price inflation of five percent, the other ten percent.  In the latter case real government spending is falling by ten percent, a bigger decline than for the first society.  But can we properly conclude that the second society will be having a bigger problem of aggregate demand?  No, the price level is going up ten percent!  The erosion itself is being caused by higher nominal demand.

If real government spending is declining because of price inflation, that fact, taken alone, is unlikely to be associated with an aggregate demand problem.  After all, we are not talking about inflation induced by oil price hikes.  We are talking about inflation pushed along by…demand.

One of the trickiest problems in economics is knowing when the “real” variable can be a misleading metric.

More generally, consider this Marcus Nunes post: “For the whole period depicted in the chart the correlation between real output growth and real G growth is significantly NEGATIVE!”  That is of course in part the result of an identification problem (fiscal policy often becomes more active in bad times), but look at the last few years of the chart only.  What you will see is a murky story that, no matter what machinations and Ptomelaic epicycles you may get from some of the more polemic Keynesians, is not well illuminated by Keynesian economics in the traditional sense.

Here are some other chart comparisons.

It is fine to say it is murky.  It is murky.  Murky, murky, murky.  But from that we should not conclude that fiscal policy is extremely effective, as it probably is not in most cases.  That is part of what murky implies.

Here is Scott Sumner with questions for Keynesians, all of them on the mark, read the whole thing.

NB: If you read this post as arguing “there was no aggregate demand problem in years ????”, go to community college!

Or if you read this post as saying “Cowen thinks nominal government spending is the correct measure of austerity…and that is wrong…”, well, go back to high school!  There is no “correct measure,” it depends on the question you are asking and even then more than one measure may be relevant.

Kevin Drum on Charter Schools

by on January 12, 2015 at 3:04 pm in Economics, Education | Permalink

Kevin Drum reports two factlets.

First: Neerav Kingsland says that SAT scores of new teachers are rising and that most of them are staying in teaching for at least five years. He comments: “If I was going to bet on whether American education will improver, flatline, or get worse — I would look very hard at the academic performance of teachers entering the profession, as well as how long these better qualified teachers stayed in the classroom. The aforementioned data makes me more bullish on American education.”

Second: Adam Ozimek says we’re selling charter schools short when we say that on average they do about as well as public schools. That’s true, but there’s more to it:

I would like to propose a better conventional wisdom: “some charter schools appear to do very well, and on average charters do better at educating poor students and black students”. If the same evidence existed for some policy other than charter schools, I believe this would be the conventional wisdom.

….The charter sectors’ ability to do better for poor students and black students is important given that they disproportionately serve them….53% of charter students are in poverty compared 48% for public schools. Charters also serve more minority students than public schools: charters are 29% black, while public schools are 16%. So not only do they serve more poor students and black students, but for this group they relatively consistently outperform public schools.

That is a new NBER Working Paper by Angrist, Autor, Hudson, and Pallais.  Here is the sentence of interest for the recent community college initiative:

Awards offered to prospective community college students had little effect on college enrollment or the type of college attended.

Do note that some other kinds of awards appeared to be more effective, so this is not an anti-subsidy result per se.  And here is a new Bulman and Hoxby paper on federal tax credits and the demand for higher education (not just community colleges):

We assess several explanations why the credits appear to have negligible causal effects.

Making these programs work is not so easy.  Reihan Salam offers good points, so does Arnold Kling.

Here is a 2010 research paper (pdf) by Schenk and Matsuyama, and here is one sentence from the abstract:

Our results show returns are six percent for those completing a community college degree.

Other work shows that fewer than forty percent of those who start will finish with a degree-based reward and that number may be lower yet for the marginals who are not currently enrolled.  Of course those who do not complete will waste some time and money along the way, although the learning may raise their productivity somewhat.

The overall return on additional subsidies to community college participation is therefore…?

The initial pointer is from @herdingbats.

Assorted links

by on January 12, 2015 at 12:51 pm in Uncategorized | Permalink

1. Book preview for 2015.  Good stuff, including volume four of Knausgaard, a new Stephenson, a new Gaiman, a new Ishiguro, a Philip Glass memoir, perhaps the Niall Ferguson book on Kissinger will be interesting too.  Here is another preview list.  And who was nominated for a literary Nobel Prize in 1964.

2. The pick-up culture that is Chinese.

3. Another (right-wing?) view on why the leading public intellectual economists are left-wing.  And more from Krugman.

4. Voodoo and Haitian mental health.  And the culture that is Singapore.

5. Sri Lanka’s surprise (positive) political transition.

6. Summers responds to Andreessen on secular stagnation.

Our newest MRUniversity online course in economics is now starting, Principles of Microeconomics! Tyler and I have created what we think is our most engaging course yet — featuring high production quality videos filled with great examples to illustrate key concepts.

We’ll cover all of the important topics in microeconomics, such as competition, monopoly, price discrimination, externalities, public goods and more. There are practice questions along the way to test your knowledge, and don’t hesitate to post your questions on each video page.

Check out our video introducing the course and economics more generally. We begin with a great story about incentives!

That is a new (early 2014) and excellent book by Elaine Scarry, the subtitle is Choosing Between Democracy and Doom.  Here is one good sentence:

…the British government arranged a secure fallout shelter for 200 leading officials, it neglected to include the queen in its plans…

Here is a more thematic sentence:

The impossibility of “governing” nuclear weapons emerges across many pages of this book.

Recommended, and consistent with my long held view that the production of nuclear weapons represented one of the most fundamental revisions of the U.S. Constitution.  The discussion of nuclear submarines, and how hard it can be to send them revised orders, is both fascinating and scary.

Here is some testimony from 2011 (pdf), by Mason M. Bishop:

…the myriad of job training programs funded by multiple federal agencies needs to be curtailed.  Currently, the U.S. Department of Energy, the U.S. Department of Health and Human Services and the National Science Foundation are all funding community college education and training grants.  The proliferation of funding for post-secondary education and training programs from Federal agencies with no experience in education and training issues, only serves to foster “mission creep,” duplication of effort and a waste of valuable resources.

Here are my earlier remarks on the new community college subsidies proposal.  Here is Mason Bishop on Twitter, with further remarks.

The review is excellent and interesting throughout, here is one good bit:

Come to think of it, lack of intelligibility runs like a red thread throughout Average is Over, from “ugly” machine chess moves that human players scratch their heads at, to the fact that Cowen thinks those who will succeed in the next century will be those who place their “faith” in the decisions of machines, choices of action they themselves do not fully understand. Let’s hope he’s wrong on that score as well, for lack of intelligibility in human beings in politics, economics, and science, drives conspiracy theories, paranoia, and superstition, and political immobility.

Cowen believes the time when secular persons are able to cull from science a general, intelligible picture of the world is coming to a close. This would be a disaster in the sense that science gives us the only picture of the world that is capable of being universally shared which is also able to accurately guide our response to both nature and the technological world.

Read the whole thing, the pointer is from Arthur Charpentier.

Assorted links

by on January 11, 2015 at 12:56 pm in Uncategorized | Permalink

1. The importance of sociologist Howard Becker in France.  And Harry Jaffa has passed away.

2. Many variants of Moore’s Law are now over.

3. 25 predictions about media and the internet.

4. How to convert your Mercedes into a self-driving Mercedes (sort of) and impress your date.

5. Duolingo.

6. Paul Krugman on why there is no right-wing Paul Krugman today.

7. Jeff Denning on the economics of community college.

More than 220k, apparently:

The gang allegedly numbered 18-20 people and spent $220,798 on the attack, including $4,000 on two sniper “Barret” .50 calibre rifles that the accountant who compiled their expenses said were “not really necessary, but could be very useful”. Each man had $4,000 to cover costs while they were in Gambia.

But the coup attempt failed and this week, US federal prosecutors charged a Texas businessman with conspiring with a former US Army sergeant and others to orchestrate an attack in Gambia on the last two days of 2014.

There is more here in the FT.  And here is a tidbit of note:

US authorities accuse Cherno Njie, a 57-year-old US citizen of Gambian descent who made a small fortune in the housing industry in Texas, of bankrolling the coup.

The article is interesting throughout, there was at least the ostensible motive of restoring democracy to the country.  I wonder to what extent he viewed this as a philanthropic rather than selfish venture.

David Leonhardt writes:

The plan — which would require congressional approval — would apply to students attending a two-year college, including part time, so long as the college offered credits that could transfer to a four-year college or provided training that led to jobs.

David’s article is excellent and has much useful information:

As Reihan Salam of National Review notes, community college tuition is already low. In fact, it’s zero, on average, for lower-income families, after taking financial aid into account. Vox’s Libby Nelson wrote, “Community college tuition for poorer students is often entirely covered by the need-based Pell Grant.”

One potential implication is that by making community college universally free, the government is mostly reducing the cost for higher-income families.

Calculating the completion rate at community colleges is difficult, this estimate does some work to get it up to 38 percent.  What would the completion rate be for the marginal students encouraged under the Obama plan?  We don’t know, but I’ll guess at 20-30%, no more.  That’s the real problem.

Furthermore some of the value of education is signaling to the labor market that you are able to finish college.  I do think the learning component of education is generally more important, but for “marginally not attending community college individuals” — who are often regarded with suspicion by employers — I would not be surprised if the signaling component were one third or more of the value of a degree.  To that extent, pushing more marginals into the degree funnel lowers the value of the degree for the others who were getting it already by lowering the average productivity of the pool of finishers.  That would lower the efficiency gains from the program and also partially offset some of the intended distributional consequences.

Mike Konczal likes the idea, and believes it may lower higher education prices more generally.  Libby Nelson at Vox considers it to be a middle class benefit.  Neil McCluskey at Cato is negative.  Carrie Sheffield is critical.  Here is a look at potential winners and losers in the higher education sector.  The plan could lead to federal money replacing state money, rather than leveraging it.

Citing the growing economy and improving labor market, Andrew Flowers noted:

college enrollment is declining for recent high school graduates (those 16 to 24 years old). And it’s falling fastest for community colleges.

Overall my take is that the significant gains are to be had at the family level and at the primary education level, and that the price of community college is not a major bottleneck under the status quo.

From this graph I concluded one of two things must be true depending on one’s definition of austerity.

Either austerity means nominal cuts and we never had any of it, or austerity means cuts relative to trend and we are still savagely in its grasp.

Relative to the 2000-2009 decade trend, total government spending is roughly 35% lower in q3 of 2014 than it should be. Hard to say austerity is over by that metric.


The full link is here.  As I wrote in an email to an unnamed correspondent earlier today: “I gladly admit that reading me in 2006 was not a good guide for what happened in 2007-2008.  A bunch of those guys should admit the same about the current day…”