22 June, 2014

Notes From All Over (22/06/14): Rise of the West, Island Disputes, & Too Much Stuff About China

A collection of articles, essays, and blog post of merit.


"The Little Divergence"
'Pseuderoerasmus,' Pseudoarasmus (12 June 2014)
In this blogpost I will argue the following :
  • While very few economic historians now dispute that East Asia had lower living standards than Europe well before 1800,
  • …there is no agreement on whether European economies prior to 1800 were “modern” or “Malthusian” ;
  • … if they were Malthusian, then the “little divergence” is rather trivial and unremarkable.
  • Furthermore, the income “data” for years prior to 1200 are mostly fictitious.
  • While real data exist after 1200 for Western Europe and China, output estimates are still calculated using assumptions that, were they better understood, would shatter confidence in the enterprise of economic history !
"Addendum to The Little Divergence"
'Pseudoerasmus,' Pseudoarasmus (12 June 2014)

Two of the most popular posts on the Stage are "The Rise of the West: Asking the Right Questions," and "Another Look at the Rise of the West, But With better Numbers," which take as their subject global energy consumption and wealth production on a millennial time scale.  Pseudoerasmus--who chimes in regularly in the comments section here--has written a series of posts that put most of this analysis in question, arguing that the Madison and Broadberry data-sets these posts use cannot be relied on.

Both posts are admirable examples of how to write about technical social science debates found deep in the literature and present them in an engaging fashion without dumbing the content down. Strongly recommended. 

China’s Information Management in the Sino-Vietnamese Confrontation: Caution and Sophistication in the Internet Era
Andrew Chubb, South Sea Conversations (9 June 2014).

China’s expanding Spratly outposts: artificial, but not so new
Andrew Chubb, South Sea Conversations (19 June 2014).

Andrew Chubb's South Sea Conversations (讨论南海) is the first website I check whenever things get hot in the South China Sea. Both of these pieces - the first published formally in the Jamestown Foundation's China Brief, the second a blog post of the more standard type - are examples of the site's general excellence.


"The Causal Effects of Father Absence"
Sara McLanahan, Laura Tach, and Daniel Schneider, Annual Review of Sociology, Vol 39 (2013), pp. 399-427.

I recommend this paper for two reasons:
  1. It provides strong evidence that fatherhood does matter, and that divorce or single parenthood affect child outcomes in substantive ways. These outcomes are all social, emotional or academic in nature; the study affirms that there is no evidence for any causal relationship between father absence and adult economic outcomes or child cognition (e.g. IQ scores).
  2. I have recently warned about the "Cross Section Illusion" and the pit-falls that come from relying too much on cross sectional data. The second section of this paper, which reviews the methodology of 40 or so studies on family structure and child outcomes, is a superb overview of the different methods social scientists have tried to avoid these problems. This discussion is almost as interesting as the results of the study itself. 

"Mike Lotus Meeting with Emmanuel Todd in Paris, Discussing Todd’s Current Work and America 3.0, UPDATED"
Michael Lotus, America 3.0 Institute Blog (17 June 2014).

Note the replacement of the old America 3.0 blog with a full blown America 3.0 Institute. The Institute can be followed on twitter here

List of Passages I highlighted in My Copy of Jonathan Haidt's "The Righteous Mind"
Scott Alexander, Slate Star Codex (12 June 2014).


"ELI5: What happens after Chinese students go to college in the US, then return to China with knowledge of events like Tiananmen Square?"
Comment by Greenpapaya. reddit/r/explainlikeimfive (4 June 2014).

A few of you may have had the misfortune to read Max Fischer's ignorant Vox write-up on what Chinese millenials know about the Tiananmen Massacre (or the video Fischer posted to accompany it). This reddit comment, written by one of those semi-mythical, brain-washed Chinese university students, is a proper corrective. If someone asks what the average urban jiulinghou knows about the June 4th incident, please just give them this. 

See also: "The Day After," A.E. Clark, Ragged Banner Press (5 June 2014).

"China Will Need a Series of Economic Miracles to Sustain Growth"
John Maudlin and Wroth Wray, Business Insider (9 June 2014)

Bearish takes on the Chinese economy are not uncommon; this is one of the best examples of the genre I have had the pleasure to read.

Decoding China’s Emerging “Great Power” Strategy in Asia
Christopher K. Johnson, Ernest Z. Bower, Victor D. Cha, Michael J. Green and Matthew P. Goodman (Washington DC: Center for International and Strategic Studies, June 2014).

Annual Report to Congress: Military and Security Developments Involving the People’s Republic of China 2014
Office of the Secretary of Defense (Washington DC: Department of Defense, 2014).

Note: Both of these reports ate 80+ pages long. Read 10 pages each day to keep the PLA at bay! If nothing else, glance through the appendices of the Office of the Secretary of Defense's Annual Report. There are a few maps of the PLA's current geographic  distribution that I will be using in the future.

"Ukraine, Russia, and the China Option: The Geostrategic Risks Facing China Policy"
Andrew Small. German Marshall Fund of the United States. European Policy Paper, No. 2 (May 2014).

"The Energy Context behind China’s Drilling Rig in the South China Sea"
James Manicom. China Brief,  Vol. 14, Iss. 11 (4 June 2014)


"Iraq War: Detailed Map"
Wikipedia: The Free Encyclopedia (updated in real time)

An ideal map for following what is happening in Iraq. The map displays who holds what (updated as close to real-time as the internet allows) without all of the extra punditry that accompanies most press updates on the situation.

"Cambodia’s Impossible Dream: Koh Tral"
Jeff Mudrick, The Diplomat (17 June 2013)
The popular Khmer view of Koh Tral – as reflected in the Khmer blogosphere, in popular song, and on YouTube travelogues – is that the island which Vietnamese know as Phu Quoc is historically Khmer, that Cambodia has never relinquished its territorial claim, that Koh Tral was unfairly awarded the Vietnamese in 1954 over Cambodian protest, and that because the maritime border used a 1939 French colonial administrative line never intended to reflect sovereignty (the “Brevie Line”) international law should dictate the island’s return to Cambodia.

This view and the quest by leading Khmer politicians to secure Phu Quoc for Cambodia appears rooted in myth. It reflects a misunderstanding of the history of the island and the Khmer’s connection to it, an exaggeration of Khmer leaders’ continuing commitment to the cause of Koh Tral, and a lack of appreciation of the legal hurdles involved in wresting the territory from Vietnam in courts of international law.....

"Who's Who in the Thai Coup"
Seri Thai. New Mandela (2 June 2014).

The AK-47 of Trucks
Isegoria, Isegoria (21 October 2010).


"Living in a World That Is, Not as it Ought to Be"
Razib Khan Gene Expression (14 June 2014).
Illiberal democracy is a part of the history of the United States itself. Though most Americans have the facts at hand from their basic education to understand this, it is not at the surface of their minds because of the primacy of what I have termed “democralotry”; the concept of democracy über alles. The problem plagues the mainstream of American politics, from Right to Left. It seems that George W. Bush sincerely believed that his invasion of Iraq could result in the rise of democracy from the ashes of decades of Baathist autocracy. Though many on the Left critiqued the execution and casus belli, few adhered without flinching to a realist implication that it was unlikely that Iraq would become a liberal democracy because of the nature of Iraqi society. Americans have an idea of what the world ought to be like, liberal (in a broad sense) and democratic, and are reluctant to acknowledge that it seems unlikely that sheer will alone can produce that as the state of a given society over a short period of time. On the American Right there is an ahistorical myth of American liberal democracy emerging fully formed like Athena from the tyranny of the British. The long and complex centuries long evolution into the society which we have today is denied as liberal revisionism. On the American Left there is a strong discomfort with making observations about the differences between societies, in particular when those observations might reflect poorly on non-Western cultures when judged in light of liberal Western values, which are nevertheless implicitly assumed to be universal....

"The War College Definition of Strategy Hurts Our Understanding of Landpower"
Geoffrey Demarest, Small Wars Journal (12 June 2014).

"Small--yet Broad--Is Beautiful (or Why it is Good to Have Been British)"
Lorenzo, Thinking Out Loud (1 June 2014).
If a highly stable banking system is defined as one that has been crisis-free since 1970, then only six out of 117 countries--Australia, Canada, Hong Kong, Malta, New Zealand, and Singapore--meet the threshold for being both credit abundant and crisis free....
To have an effective bank bargain, (1) bank assets have to be protected from government expropriation, (2) minority shareholders and depositors have to be able to stop bank insiders expropriating their assets or else be compensated for accepting the risk of expropriation by bank insiders, and (3) there has to be mechanisms to protect bank insiders, minority shareholders and depositors from expropriation by borrowers or else be compensated for accepting the risk of expropriation by borrowers.
Since 1970, six jurisdictions have managed to do all that. Why so few jurisdictions? Because governments face conflicts of interest in managing the game of bank bargains....


How To Make A $454 Homemade Air Conditioner For About $15
The Good Survivalist The Good Survivalist (13 April 2013)

"Social spiders let their personalities choose their jobs"
John Timmer, Ars Technica, (1 June 2013).

Another point for group selection theory.


13 June, 2014

Chinese Cookery: Notes on the History of Chinese Stir Fry

When asked by Chinese acquaintances if I enjoy Chinese food more than American cuisine I often reply, “I like Chinese food. The problem is, Chinese food does not like me!” I speak this truthfully. Few national cuisines can compare with the savor of Chinese cookery. Alas, what is pleasing to the tongue does not always please the belly. During my last trip to Beijing I learned this lesson all too well—I was not three weeks in the country before recurring attacks on my stomach had me doubled over, each assault of greater violence than the last. The advice I frantically found on every medical website only deepened my misery. "Step #1,” they read, “don’t eat any oily foods until your stomach has recovered.

These advice-givers had obviously never tried living in China. In Beijing you will have better luck finding beverages that contain no water than finding a full course meal with nothing cooked in oil. 

I survived the experience on skipped meals, steamed buns, small bowls of plain white rice, and frequent trips to cheap Japanese restaurants where oil is not the central ingredient. Surprisingly, this dismal experience did not diminish my fondness for Chinese cuisine--though I must admit I remain leery of committing myself to any diet whose chief entrees are all stir-fried again. 

The famed sages and heroes of Chinese antiquity would probably face Beijing's oily cuisine with similar trepidation. As Endymion Wilkinson notes in the unparalleled historical trivia-fest that is Chinese History: A New Manual, Chinese style stir-fry is a fairly recent invention:
The modern word for stir-fry is chao (炒)…. Chao only appears in the Tang sources in the context of roasting tea-leaves, but it is mentioned in about 12 Song recipes. By the Ming, stir-frying (which is not found in other cooking traditions) was becoming more common and by the Qing it was differentiated into many specialized procedures….

Even so, only five or six out of a total of 100 recipes in the sixteenth-century novel Jin Ping Mei are stir fry recipes, and wok dishes only accounted for about 1% of the recipes in the most famous eighteenth century recipe book, Suiyuan shidan. Despite this there are signs that stir-frying was spreading. This was no doubt in part linked to the desires to prepare food as quickly in possible to conserve fuel, which was increasingly rare and expensive in and near big cities by the late Ming….
Another factor encouraging the spread of stir frying was the increasingly commercial nature of city life in the late Ming and Qing. People were in a hurry to be served (compare colonial America where frying was used for breakfast because the farmers were in a rush to get to work with the animals and in the fields. By midday when the sun was high and too hot for working, there was more time, so the old methods of steaming, roasting, and baking were preferred). By the late Qing a wok range (chaozao or paotai zao) became standard in most kitchens. It had a large space for the fire and wide apertures in the top in which to sink the bottom half of the wok into the flames. When a surge in heat was required an assistant, acting on the shouted instructions of the cook, fanned the stoking hole at the back of the range.

In the twentieth century the old portable charcoal stove was gradually replaced by various more efficient ones, for example, beehive coal briquette stoves, or kerosene, diesel, or gas stoves. These provided a reliable and easily adjusted heat source and were ideal for the small family kitchen as well as for the itinerant producer of quick meals using a single wok. Their huge disadvantage was that they were often the cause of ruinous urban fires.
The widespread overuse of oil with stir-frying (much commented on by foreign observers starting in the nineteenth century), was a late appearing aberration that should not be allowed to detract from the unique advantages of stir-frying, properly executed.

 So how do modern Chinese eaters respond to Chinese cuisine of the pre-chao world?  Wilkinson conducted an experiment to find out:
“As an experiment, during a three-month period in Beijing winter of 1999-2000, I asked my chef to prepare dishes on the basis of cooking methods, ingredients, and recipes found in the early sixth-century Qimin Yaoshu . The ingredients included many grasses, for example, bulrush and fibrous plants difficult to find today, but not unpleasant to anyone fond of vegetarian cooking. To say the least, the dishes are thick with taste, because they are seasoned with pastes made of fermented meat, fish, or soybean and cooked with fermented black beans. I found that the absence of later ingredients, such as soy sauce, vegetable or peanut oil, sugar, chili, and tomatoes a welcome break and the use of boiling, roasting, or baking a relief from the monotony conferred by oily stir fry which is so often encountered today. However, most of my Chinese guests felt that what they were eating was foreign, not Chinese.

Perhaps more predictable was the Shang dynasty restaurant that opened in Guangzhou in the early 1990s. It served reconstructions of Shang period dishes, but closed within weeks of opening, because its customers, brought up on Cantonese cooking, found its dishes totally alien.” [2]


[1] Endymion Wilkinson, Chinese History: A New Manual (Cambridge: Harvard University Press, 2013), p. 459 section 36.17.1.

[2] ibid., p. 442, box 63, section 36.1.

11 June, 2014

Hard Truths and Hidden Gems at Shangri-La

Prime Minister Shinzo Abe delivers the keynote address at the 2014 Shangri-La Dialogue

Image Source
This weekend I finally had the chance to sit down and read the collected transcripts of the 2014 Shangri-La Dialogue. This year's round of the Dialogue has garnered much more media attention than usual. The coverage has focused on the speeches delivered by Shinzo Abe, Prime Minister of Japan, Chuck Hagel, Unites States Secretary of State, and Wang Guanzhong, Lieutenant General and the Deputy Chief of Staff for the People's Liberation Army. Secretary Hagel's remarks, in particular, were more pointed than is usual for a multilateral forum of this type, and by explicitly calling China out by name they represent a departure from the more conciliatory rhetoric that has defined Washington's approach to China for most of the last decade.
Most of the coverage and analysis has centered on these three addresses. This is a shame. It is appropriate to give official pronouncements the attention they are due, but to read these exclusively is to miss the most insightful remarks of the Dialogue. Much has been said, for example, about Lt. General Wang's official response to Mr. Abe and Mr. Hagel, but I was much more struck by the impromptu  exchange between Hagel and a different Chinese general during the former's "Question and Answer" session the night before: 

Major General Yao Yunzhu, Director, Center for China-America Defense Relations and Research Fellow, Academy of Military Science, People's Liberation Army
Thank you. Thank you, Secretary Hagel, for your very powerful and straightforward speech.
My question is: do you consider that nationalization of the Diaoyu Islands in 2014 a consolidation of status quo in East China Sea or a unilateral challenge of the status quo? And do you consider sovereignty is equal to administrative, administration, because your position, the US position, is to take no position of sovereignty, but your defence treaty covers the disputed Diaoyu Islands, because it is under the administration of Japan?

And when a US ally in the region comes into conflict or a clash over a disputed territory, the United States has repeatedly declared its defence commitment or declared, defined, clarified that the defence treaty covers the disputed matter. Do you think it is a sort of threat of force, coercion or intimidation?

Dr John Chipman, Director-General and Chief Executive, IISS
Thank you.

Major General Yao Yunzhu, Director, Center for China-America Defense Relations and Research Fellow, Academy of Military Science, People's Liberation Army
I have a last one, a last question.

Dr John Chipman, Director-General and Chief Executive, IISS
No, but I think –

Major General Yao Yunzhu, Director, Center for China-America Defense Relations and Research Fellow, Academy of Military Science, People's Liberation Army 
I have a last question about ADIZ. There are some 20 countries in the world which have set up ADIZ. Most of them are US alliances and the ADIZ had been set up 60 years ago during the Cold War. What international law did the US apply to when they set up their ADIZ? What international organisation had the United States asked for permission or what country had the United States consulted to before they set up its ADIZ? So what international law has China violated in setting up an ADIZ in East China Sea? And why do you think that the US practice –

Dr John Chipman, Director-General and Chief Executive, IISS
General –

Major General Yao Yunzhu, Director, Center for China-America Defense Relations and Research Fellow, Academy of Military Science, People's Liberation Army
- and the practice of its alliance of ADIZ is the international norm that every country in the world should apply to? (Color emphasis added)  [1]

I cannot summarize the common Chinese perception of American hypocrisy and perfidy better than Major General Yao does here. Secretary Hagel's answer was a tad disappointing; he manages to sidestep General Yao's real questions with the sort of meaningless wish-wash politicians everywhere use when they want to dodge public commitments they are not prepared to make. This shouldn't be too surprising--there was not a speaker at the conference who answered any differently. It was not the speaker's answers that make the Q&A session's valuable, but the nature of the questions they were given.

Here are two other examples from the same session:

Tadakazu Kimura, Chief Executive Officer and President, the Asahi Shimbun

Thank you very much, Mr Secretary and Dr Chipman.

It is no doubt that the United States’ presence in the Asia-Pacific region is indispensable, as a strategic counterweight. President Obama assures the US engagement is in the region as a strategic rebalance. However, the question we face is in reality how long can the US afford to continue to engage in the vision, given the current serious fiscal condition? My concern is the US suggests a power projection in the region could tip the power balance [Inaudible] and transform the geopolitical landscape here. Consequently, do you think Japan should shoulder a much heavier burden, not only in the non-military facets, but also in the military operation field as a partner of the US–Japan alliance? Thank you very much......

Lieutenant General (Retd) P.K. Singh, Director, United Service Institution of India

Coming to my question, I think we are seeing a little bit of assertive, not a little bit, assertive behaviour by China and we will have some fait accompli presented to us. Whether the fait accompli is on the land or on the sea, it is difficult to reverse. And we can keep talking in the various fora, nothing will change. So my question is, sir, how do you revert the changed status quo back? Is the architecture adequate that exists here today and, if not, what should we do? Thank you, Secretary. (color emphasis added) [2]

The questions are direct and--as far as anything coming from a think tank fellow or government official is concerned--succinct. They have to be. If they are to ask their question in the thirty seconds allotted and try to get a meaningful answer in return, the questioners must avoid politcobabble and speak with clarity and candor. That none of these questions are considered "official" statements further lowers the costs of this candor. Question time is the one public event at Shangri-La where the attendees must speak their mind. If you wish to see how the policy making and opinion shaping elites of each nation perceive recent developments in the region, they are not a bad place to start.

The United States’ Contribution to Regional Stability: Q&A
Questions Addressed to: Chuck Hagel, U.S. Secretary of Defense
Shangri-La Dialogue2014 1st Plenary Session (31 May 2014)

Major Power Perspectives on Peace and Security in the Asia-Pacific: Q&A
Questions Addressed to Lieutenant General Wang Guanzhong, People's Liberation Army, and Anatoly Antonov, Russian Deputy Minister of Defense
Shangri-La Dialouge 4th Plenary Session (31 May 2014)


[1] Quoted from International Institute for Strategic Studies,  "The United States’ Contribution to Regional Stability: Q&A," Shangri-La Dialogue 1st Plenary Session (31 May 2014).

[2] Ibid.

07 June, 2014

The Cross Section Ilusion

The side-bar of this blog declares that the Stage is a space to discuss "the intersections of governance, ecology, demographics, and culture." [1] This casts a wide net--at times, too wide of a net. It would be much easier to maintain a blog devoted solely to exploring the 'dynamics of human civilization,' chronicling the decline of America's republican institutions, describing the intricacies of the Chinese strategic tradition and Chinese military history, analyzing contemporary Asian geopolitics, or any of the other recurring sub-themes long term readers of the Stage are familiar with than trying to mash them all together on one site. I keep the purview of the Stage open-ended for a reason: none of these topics can be truly understood in isolation. It is difficult to approach the most exciting questions and the most intriguing theories of our day without crossing disciplinary boundaries. The ecologist and the economist, the psychologist and the strategist, and the archaeologist and the political analyst all have a great deal to teach each other. Reality is not a one trick pony.

It is for such reasons we spend a great deal of time here discussing odd correlations for all sorts of things, trying to discern the connections between variables as different as genetics, climate, family structure, language, and other factors easily looked over and forgotten. This kind of analysis is both fun and necessary, but it must be done with care. It is too easy to get caught up in sloppy thinking when playing this game. I call a particularly common lapse the  "Cross Section Illusion."

An excellent introduction to the Cross Section illusion and its attendant problems is a recent study by Roland Sturm and An Ruoping published in CA: A Cancer Journal for Clinicians The authors both come from RAND Corp, and as might be expected, write with the statistics crunching style RAND is famous for. Their chosen topic is America's worsening "obesity epidemic." Sturm and An suggest that both policy makers and the general public hold faulty ideas about the epidemic's origins that could be avoided if researchers relied less on  cross sectional studies and more on time series data.

To get a sense of the difference between the two, consider the following:

Cross Section:
Obesity rates by race and sex among U.S. adults, 2011/2012.

Taken from Cynthia L. Ogden,; Margaret D. Carroll, Brian K. Kit, and Katherine M. Flegal, "Prevalence of Obesity Among Adults: United States, 2011–2012," NCHS Data Brief, no. 131 (Washington DC: Center for Disease Control and Prevention, October 2013).

Time Series:
Increase in Body Mass Index of U.S. adult women, by race or ethnic background, 1986-2012.

Taken from Figure 1, Roland Sturm and Ruowang An, "Obesity and Economic Environments," CA: A Cancer Journal For Physicians (22 May 2014, accessed June 2014).

Cross Section:
U.S. Adult Obesity Rates by Age and Education Level, 2008.

Taken from College Board,  "Trends in Higher Education: Adult Obesity Rates by Age and Education Level, 2008," Trends in Higher Education: Figures and Tables (accessed June 2014). Original Data from the CDC's National Center for Health Statistics (2008).

Time Series:
Increase in Body Mass Index of U.S. adults, by education level, 1986-2012.

Taken from Figure 1, Roland Sturm and Ruowang An, "Obesity and Economic Environments," CA: A Cancer Journal For Physicians (22 May 2014, accessed June 2014).

Cross Section:
Prevalence of Self Reported Obesity Among U.S. Adults, 2012.

Taken from "Obesity Facts," Center for Disease Control and Prevention (28 March, 2014; accessed June 2014).

Time Series:
Prevalence of Obesity in U.S. Adults from California, Colorado, and Mississippi, 1990-2012.

Taken from Figure 2, Roland Sturm and Ruowang An, "Obesity and Economic Environments," CA: A Cancer Journal For Physicians (22 May 2014, accessed June 2014).

If you are concerned with American obesity rates and turn to the cross sectional data to try and figure out what is going on, it is easy to reach a flawed conclusion. The correlation between education and obesity, for example, seems quite clear. The poorer and less educated an American is, the more likely he or she is to be obese. Looking at this data it seems reasonable to suggest that something about poverty is making people more obese--perhaps cruddy processed food is the only thing America's poor and less educated can afford to buy, or maybe the poor live in urban areas where people do not exercise. These hypotheses are plausible... until you look at the time series. It then becomes apparent that the rich and educated are gaining weight at the same rate as the poor.  Poverty cannot explain this.

Sturm and An make a similar point about geographic explanations of the obesity epidemic, poking fun at the Colorado Diet in particular:
What about geographic differences? There is a famous set of maps by the Centers for Disease Control and Prevention that illustrate the changing obesity prevalence by stage since 1985. However, some interpretations of these maps seem to confuse cross-sectional differences with changes over time. A new diet book about the “Colorado diet” includes the following description by the publisher: “Americans are getting fatter. A third of them are now obese–not just a few pounds overweight, but heavy enough to put their health in jeopardy. But, one state bucks the trend. Colorado is the leanest state in the nation, but not because of something in the air or the water.”
Figure 2 shows the prevalence of BMIs of over 25 kg/m2 (ie, overweight or obese) over time for Colorado (the state with the lowest average BMI or overweight or obesity rates), California, and Mississippi (the state with usually the highest rates). The overweight/obesity rates in Colorado do lag behind those in Mississippi, but we see no evidence of any “bucking the trend.”....To understand the obesity epidemic, rather than asking a question such as “Why are people in Colorado thinner than people in Mississippi?” we need to ask why are people in Colorado gaining weight at the same rates as people in Mississippi? (emphasis added) [2]
The authors continue with the myth-busting for the rest of the paper, ending up with a simple and sensible explanation for rising obesity rates. I encourage those interested in this issue to read the entire thing. But I bring it up here because of the larger issue it illustrates. It is very difficult to make meaningful claims about causation--or even correlation!--on the basis of cross section data alone. Often times seemingly perfect, statistically significant correlations disappear when the same variables are viewed over a longer stretch of time. In other cases-as in this one-time series data reveals that the real story isn't about variance between two groups at all, but about the rate at which each group is changing. It is all too easy to be fooled by the Cross Section Illusion.

This is worth keeping in mind the next time someone uses a few cross sectional studies to try and convince you that a correlation between wealth, violence, political systems, genes, geography, or whatever else may be the flavor of the day should be taken more seriously. They may be right--but before you cede the point, be sure to check if the time series version of the data supports their claim.


[1] This is how it reads at the time of this writing:  7 June 2014.

[2] Roland Sturm and Ruowang An, "Obesity and Economic Environments," CA: A Cancer Journal For Physicians (22 May 2014, accessed June 2014).