Sunspot and Animal Spirit

05/05/08 revised

(Case Study)
Japan had a big recession for 10 years. Many people were unemployed and had to look for a job.


Recession is so strange: many people can’t live a good life even though they are in well developed society. Price goes down, but simultaneously income goes down. Generally, price goes down more slowly than income. So many people have a hardship in their life.

Recession can always occur in developed countries, because there are a lot of goods there and also people are rich already. If people do not want to buy goods any more for some reason, salespeople cannot sell goods even at lower price, they cannot get income and thus they cannot buy any more. And then, price goes down, income goes down,... It is, what is called, a deflationary spiral.

By the way, why people don’t want to buy goods any more? People feel nervous about buying goods. Why people are so nervous? It’s a psychological matter. Nobody knows. It depends on the situation that people are having. It can be explained by the "sunspot theory".


"Most, probably, of our decisions to do something positive, the full consequences of which will be drawn out over many days to come, can only be taken as the result of animal spirits - a spontaneous urge to action rather than inaction, and not as the outcome of a weighted average of quantitative benefits multiplied by quantitative probabilities."
(The General Theory of Employment Interest and Money, 161-162)

If you are a graduate student and have taken macroeconomics 1&2 and learned dynamic programming already, you should know about what the sunspot theory is.
(Downloaded from Roger E. A. Farmer)

Note that the sunspot theory doesn't look like the idea of the Neoclassical (King-Plosser type) RBC model or the Keynesian (Kiyotaki-Blanchard type) imperfect competitive models.

The point is that the equilibrium is self-fulfilled. The path to the equilibrium is undetermined and moreover the multiple paths can happen. Nobody knows what equilibrium will happen.

Some economists really support this theory. It seems to me that it describes well the real economy. What do you think of it? Especially if you like RBC, what do you think of this theory?
Let me listen to your idea.

休みたいなら辞めろ

連合（日本労働組合総連合会）の高木剛会長は2008年4月26日、東京都内で開かれたメーデー中央大会で、「休みたいなら辞めればよい」と発言したとされる日本電産の永守重信社長を強く批判した。
…

永守社長は4月23日の記者会見で

　　「社員全員が休日返上で働く企業だから成長できるし給料も上がる。たっぷり休んで、結果的に会社が傾いて人員整理するのでは意味がない」

と発言したと報道され、論議を呼んだ。この「経営最優先」の発言については、高木会長も労働団体のトップとして黙っていられなかったようだ。

　高木会長は、「仕事と生活の両立」を指す「ワーク・ライフ・バランス」の必要性を強調する中で、反面教師として日本電産社長の発言に言及。「休みたければ辞めればいい」発言については「この会社の時間外・休日労働の実態を調べてみたい」とした上で、「休日返上で働くから成長できる」との発言に対しては

　　「まさに言語道断。労働基準法という法律があることを、また、労働基準法が雇用主に何を求めていると思っているのか、どのように認識されているのか。ぜひ問いただしてみないといけない、そんな怒りの思いを持って、この日本電産のニュースを聞いたところであります」

と憤りをあらわにした。　これに対して舛添厚労相は、直後の来賓あいさつで

　　「労働関係法令はきちんと遵守してもらわないといけない。きちんと調査し、指導すべきは指導し、法律にもとるものがあれば厳正に処分する」

と応じた。

4月26日20時15分配信 J-CASTニュース

つねに経営者と企業家との対立は労使交渉の上では当然であり、小生はどちらの側にもつかない。ただ、経営者としては会社の業績を上げないといけないので、社員に懸命に働いてもらわないと困る。また、社員の側としては家族と過ごしたり、肉体的精神的疲労の回復は必要となろう。体を壊してまで働くとは、何か矛盾しているようにも思える。

ただ、今回の永守氏の発言は、永守氏らしい発言といえよう。実は小生永守氏に会ったことがある。子曰く、「サザエさんのエンディングソングを聴くのが嫌いなやつは、要らない」のだそうだ。

つまり、月曜日が来るのが嫌いなやつは来なくていい、という旨の発言であるが、これは経営者からすると、小生至極もっともに思う。

前にいた会社で働いていた頃、小生『こち亀』（サザエさんの後番組）が嫌いになった。これではダメだと思って、辞職願いをいつ書くか迷った記憶がある。何しろ、入社してまもなく辞職願いを書くとは思っても見なかったことであるから。

経営者、労働者それぞれ違う立場にいるので、大いに議論と交渉を展開すればいい。ただ、労働者が経営者の側に立ったり、逆に経営者が労働者の側に立つのはむしろ不自然だ。

連合は、ただ経営者を批判するのではなく、上がった成果をきちんと労働者に配分し、労働者の側が企業の経営に対してもっと発言、並びに参画できる機会の拡充に向けた施策を提案すべきであるといえる。

日本へ向けて

04/26/08　修正

これは当初から予期していたことでもあるが、今年をもって米国を離れなければならないこととなった。

成績が思うように振るわず、英語にも問題があったために、奨学金が下りず去ることとなった。当初の目標を貫徹できなかったという意味で残念であるが、こちらの教授から「去るべきだ」という指摘を受け、気持ちはすっきりした。

しかしながら、自分が志望する経済学への関心は萎えていない。ただ、今後は「研究者」としてではなく、「実務家」として経済学を就業生活の中で磨いていきたい。

これまでを振り返るに、やはり将来に対する漠たる不安が来米当初からあり、これが成績不振への遠因になったものと考えられる。

また、評価が米国では違うことを知っていたが、それになじめなかったのも一因となろう。英語は時間をかければよくなるのかもしれないが、話す機会の少ない小生にとっては１年間の飛躍的上達は困難を極めた。 話す機会を作る努力はしたが、目的や志向の違う人たちとの社交的な会話は長く続かない。

なによりも経済学が数学を使う非常に難しい学問であることが今回の件を招いたのではなく、経済学を職として食べていくことが困難な時代になっているということを改めて実感し、このことが今回の件を招聘した。

数学については、基礎的な訓練を受け、標準的な大学院レベルの経済数学ならひととおり説明できる自信はある。しかし、何年もの長い月日をかければ、研究者やエコノミストになれるという時代はもはやなくなった。

「去らなければならない」のではなく、「去りたい」のではないか。結果論からそう認めざるを得ない。しかし同時に、実務的にしっかりとした地盤を築いていきたい、という思いもこれまでずっとあった。

人生は不安だらけ。不安があるからこそ、人は努力する。常にそう言い聞かせている。不安を楽しめ、という人生訓もこの点で成立しようが、現実的な問題を含めて、不安よりも責任を感ぜずにはいられない。米国での修士号取得を良しとして、これを励みに進歩を遂げたい。

「われ十五にして学志し、三十にして立ち、四十にして惑わず、五十にして天命を知る」といえば、三十で立てる準備をすべきなのかもしれない。

まだ迷いは晴れないでいる。しかし、人は四十にして迷わず、惑わず、己の職務を全うしたい。そのための実利的で地道な努力をしていかねばならないと感じた。これが小生の言う「責任感」である。これは、人のためではない、己のためだ。

しかし、人よりも豊かな人生を送るためには、それなりの職につかなければならない反面、自分にうそをつくような興味もないことを興味があるなどと自分に言い聞かせ続けなければならない職には就かないように努力せねばならない。

いやなこともせねばならないが、それ以上に責任感が持てる職に就きたい。

ざっと今の心境である。

このブログは引き続き、経済学ブログとして続けていく。また、英語はこれを機会に日本でも時間を見つけて練習を惜しまない。

静かなご声援のほどお頼み申したい。

Hirofumi Uzawa

Revised 9/26/2014

Hirofumi Uzawa is one of the few Japanese worldly economists, professor emeritus of Tokyo University. He originally majored in mathematics at Tokyo University, and obtained a doctorate in Mathematics.

After he became an assistant professor of the University of California, Berkeley and professor of the University of Chicago, and then professor of the Department of Economics at Tokyo University in 1969.

Uzawa initiated the field of neoclassical economic growth and general equilibrium models, though he inclined toward strictly mathematical area of economics.

Many professional economists residing in Japan can be said to have been influenced by him. I met him and Joseph Stiglitz at Doshisha University in 2003. There he talked about social common capital, which was recently of great interest to Prof Uzawa.

However, in Japan he is well known as a ruthless critic of the modern market-oriented (Lucas-Sargent-Barro type) macroeconomics. It seems to me a little strange because he had worked for modern neoclassical economics.

In the 1970s and 1980s he commenced criticizing Chicago economists, Milton Friedman, Robert E. Lucas and Gary S. Becker, for their market-oriented theories. Many of his critics were written in Japanese language and thus may not be known about outside of Japan.

One of his critics is, Rational Expectations Hypothesis (REH), which is now based on modern standard macroeconomic theory, is so unrealistic and unreasonable: people are not rational enough to forecast precisely the states of the future economy. In addition, people don't maximize their utility as the theory predicts when they consume goods and services. The economics based on REH is rather very harmful to policy decision and making in practice.

To be fair, his view on modern economics seems to lean toward political critique of neo liberalism spread all over the US and the world since the 1980s, of which the ideology is free market mechanism, privatization, deregulation, tax cut, cut in deficit government spending, and small public governance.

It can be true that modern economic growth theory has made progress partly due to his effort, but (or therefore) there are actually some economists in Japan who point out that economic research conducted in Japan became behind the time thanks to the influence of Prof Uzawa.

His academic impact on economics research in Japan was so great that many students of economics followed his critics; Modern economics based on REH had not been taught well since ever in economics departments in Japan. There are still many economists claiming that the Ramsey-Cass-Koopmans representative-agent dynasty model is a fucking crazy economics.

On September 26, 2014, Prof Uzawa passed away. He was 86. I recalled that I learned his name at Prof. Drewianka's econ 801, the Hurwics-Uzawa demand theorem and at growth text, the Uzawa-Lucas human-capital model. He blamed Milton Friedman, his ex Chicago colleague, for his market-oriented economics, but only in this point do I disagree with Prof Uzawa. It sounds to me his jealousy to him, but it's OK. There is no doubt in his greatness as an economist. Rest in Peace.

Best Macro Texts

These are 5 textbooks of macroeconomics written in English:

(1) Lectures on Macroeconomics

(2) Advanced Macroeconomics

(3) Macroeconomics of Self-fulfilling Prophecies

(4) Economic Growth

(5) Optimization in Economic Theory

(1), (2) and (3) are just macro texts that I use and like, but (4) and (5) are closely related to macro. The former is on economic growth and development, but it has a lot of analytical tools used in macroeconomics. The latter is on mathematical tools also used in macro, especially chap. 10 and 11 are very nice math resources of optimal control and dynamic programming(these are all deterministic versions of them, though).

However, the above texts are already well-known among students of macroeconomics. So, I would like to add one great text of macro in the list,

(6) Saito, M(2007), "New Macroeconomics" unfortunately in Japanese.

Every time I open it, I feel happy that I am a Japanese. This book should be really read well by many other students all over the world because it is not big but clear-cut.

Recent Macroeconomics in Japan

Recently (especially since the 1990s) the research on macroeconomics has become popular in Japan. The reason for this seems to be behind the long-lasting recession in the 1990s in Japan, especially, the heated discussion about expansionary monetary policy to cure the deflationary economy in the 1990s, such as the zero-interest-rate policy to lead the call rate to almost zero, and inflation targeting to lead the rate of price change to a particular rate of inflation, say,2-3%.

I am not a professional macroeconomist yet, but I believe that the level of research on macroeconomics in Japan is approaching gradually that in the United States.

Unfortunately, many students of macroeconomics don't seem to know about the recent macroeconomics in Japan. Of course, in many academic journals of economics, say, JPE, QJE, Econometrica, EJ, AER and so on, there are few Japanese economists. However, some Japanese economists write good graduate-level textbooks of macroeconomics.

One of them that I like most is one written by Saito Makoto of Hitotsubashi University, "New Macroeconomics".

He was a scholar of the University of British Columbia(UBC) in Canada and a student of Blanchard, an author of still great macroeconomics textbook and professor of MIT.

Although this book has been greatly influenced by Blanchard's macro text, Lectures on Macroeconomics, it is worth reading carefully. However, it has not been translated into English yet. I think that it should be translated into English and read by many grad students studying in the United States.

Japan, as you know, is the second largest economic country and it seems quite strange that economics research in Japan is not still so common across the whole world.

One of the reasons for it may be the wall of language: many textbooks written by Japanese economists are good, but unfortunately in Japanese, and moreover the lectures of economics at universities are conducted in Japanese.

If they were all in English, the Japanese economics would be much more common in the world. They should be in English as soon as possible, I hope.

Anyway, I try to report in English later what Prof. Saito says in his text. However, needless to say, it is copyrighted and so I have to say that I must not translate it and copy it in this blog.
I always have to keep it in mind when I write something important in economics.

効果のほどはいかほどか？

東京都は今年度から、受験生を抱える低所得者世帯を対象に、学習塾の費用を無利子で融資する制度を始める。　全国初の試みで、「親の経済力の格差が、子供の学力差に結びつかないようにしたい」としている。都福祉保健局によると、対象は中学３年生、高校３年生を抱える、年間の課税所得が６０万円以下の世帯。例えば、夫婦と子供１人の３人家族の場合、年収３２０万円以下、子供２人の４人家族の場合は、３８０万円以下が目安となる。　中３には年間１５万円、高３は２０万円まで無利子で貸し出す。また高３には、３校程度を上限に、大学受験料３万５０００円（１校あたり）を貸し出す。進学が決まれば返済を免除することも検討している。融資の申請は、今年８月までに、各区市町村に設置する予定の相談窓口で受け付ける。
4月17日8時50　読売新聞


いい試みではなかろうか？
しばらくこの政策の効果についてみたいが、公立学校の存在意義が今後改めて問われてくるいい機会ではないか。この政策と同時に、公立学校の教育充実、単に教員の増加ではなく、教員の質的向上（無能教員の解雇も含めた）をももくろんだ改革が必要となるように考えられる。

しばらく見守りたい。

Information Cascade

I am interested in information cascade.

Impatience Leads to Fatness and Debt

Do you know BMI? It stands for Body Mass Index. It is derived by (weight; kg)/(height; m)^2. If your BMI is more than 25, it means that you are fat!

Impatient people get fat. Let me explain it briefly:

The first problem is why we get fat.

From the experience of the United States, lower cost of meal makes us fatter. It is one of the most important factors that make us fat.

Another factor is how patient we are. How is getting fat related to how patient we are? Here's a today's topic.

Patient people can put up with their hunger today. However, impatient people can't because they don't take serious the cost of getting fat tomorrow. They take serious the benefit from eating today and so they eat more than patient people do.

In fact, one research tells that impatient people have high BMI.

Moreover, fat people are more likely to have much debt. In other words, there's a strong correlation between fatness and debt.

Why not? Impatient people spend more today than patient people do. They cannot stand up their today's desire! Impatient people don't (want to) think about paying high interest rate later. In the same way, they don't think about paying high cost of getting fat later, either.

In sum, impatient people are fat and have much debt. There are two factors that make us fat, (1)cost of meal and (2)how patient we are. Having debt and getting fat are the problem of comparing the benefit from spending today to the cost of paying tomorrow, that is, the problem of time preference.

New Monty Hall Problem

It's your life, isn't it?

受動喫煙

受動喫煙：たばこの煙とダイオキシン、細胞動き同じ　山梨大学院グループ証明　

4月10日15時1分配信 毎日新聞

他人が吸ったたばこの煙を吸う受動喫煙と同様の環境に置くと、体内の細胞がダイオキシンを取り込んだ時と同じ動きをすることが、マウスを使った実験で分かった。

山梨大大学院の北村正敬教授（分子情報伝達学）の研究グループが、世界で初めて証明した。実験では健康被害の有無まで調査しなかったが、北村教授は「高い確率で健康被害に及ぶ」と警告している。　

研究グループによると、たばこの煙は少なくとも４８００種類の化学物質を含有。ダイオキシンと同様の物質も多数存在しており、体内の「ダイオキシン受容体」と結合することで活性化し、発がん性などの毒性を発揮するという。　今回は、遺伝子組み換え技術でダイオキシンに近い物質に触れると、特殊な酵素を血液に放出するセンサーマウスを作成。このマウスを毎日、受動喫煙の環境下に数時間置いたところ、ダイオキシン受容体が活性化した。　

北村教授は「センサーマウスを使った研究は、オフィスのほこりの影響といった日常生活のリスク評価の一つしても有用」と述べた

My Econ 101

I have to teach two days later, and I am now preparing for it:

Taro's Econ 101

Price of Pepsi and Human Behavior
When the price of Pepsi rises, what should we do? It’s an easy question. We usually seek substitutes, say, Coke. The price rise makes us shift to Coke.
Price is one of the factors that changes people’s behavior.

Incentive
Economists say that people react to incentives. Incentives mean a motive for a particular action. Do people really react to incentives?

Case Study
On a teenage oral-sex craze in the United States by Tim Harford.

Oral sex is to stimulate penis or vagina by using mouth, say, fellatio and cunnilingus. Both the adults and the teenagers are related to much more oral sex than in 1990. Why not?

Schools teach the risks of sex, particularly HIV/AIDS and some other sexually transmitted infections (STI). Oral sex can be safer than penetrative sex. It dramatically reduces the risk of HIV and other STI.

(a) The economic analysis
If the price of risky sex went up and teenagers really did think about the results of their actions, they would have less risky sex, oral sex.

People switch to safer sex due to the price rise in risky sex: use of the contraceptive pill is down, but use of condoms is up. Moreover, the percentage of teenage virgins has risen by more than 15 percent since the beginning of the 1990s.

(b) Policy implication
Abortion-notification laws force teenagers to get permission to abort from their parents. Some scholars found that wherever and whenever such laws have been passed, STI rates in the teenage and adult populations start to diverge.

When it becomes more difficult to abort, teenagers seem to reduce unprotected sex.

To sum up, now we can see that people really react to incentive.

肥満、負債そして経済学

肥満と負債。一見関係なさそうであるが、大いに関係があることがわかってきた。

経済学が無用の長物であるという諦観も過去のものと感ぜずにはいられないこの研究に「人間行動の実態」に迫る経済学の気迫を覚えよう。

阪大の池田新介先生の論考を以下４つ。

（１）肥満と負債、強い相関

（２）人間心理と多重債務問題

（３）「せっかち」な人ほど肥満化する

（４）経済行動を左右する『時間割引率』

この肥満と負債の関係を説くキーワードが「時間選好率」(time preference)、「時間割引率」という概念だ。これは池田先生のご専門であるマクロ経済学、ファイナンスにおいてかなり重要な概念である。しかしながら、これは実際あまりわかっていないというのが本音であったが、近年阪大の精力的な研究によりその実態が明らかになってきたようである。

この研究は小生も高い関心をもって注目している。かなり高い政策的含意を秘めているだけではなく、経済学にある古くからある問題（たとえば「Ricardo＝Barroの中立命題」や「政策無効命題(policy irrelevance)」など）に新しい光が当てられるように感じているからである。

The Economics of Abortion

Here's the topic related to the economics of oral sex: the legalization of abortion in the 1970s reduced crime in the 1990s. The theoretical justification for this argument rests on two simple assumptions:

1) Legalized abortion leads to fewer "unwanted" babies being born.

Abortion reduces the number of unwanted children

2) Unwanted babies are more likely to suffer abuse and neglect and are therefore at an increased risk for criminal involvement later in life.

Unwanted children are at increased risk for criminal involvement, which is supported by three decades of academic research.

The effect of abortion legalization is large: as much as one-half of the remarkable decline in crime in the 1990s may be attributable to the legalization of abortion.

The Economics of Oral Sex

This issue is related to incentive: recall that people react to incentive! It's on a teenage oral-sex craze in the United States by Tim Harford.

To sum up:

Both the adults and the teenagers are engaging in much more oral sex than in 1990. Why not?

Schools teach the risks of sex, particularly HIV/AIDS and some other sexually transmitted infections (STI).

Oral sex can be safer than penetrative sex, which dramatically reduces the risk of contracting HIV and reduces the effects of some other STI. An infection that might have made a girl infertile instead gives her a sore throat.

(a) The economic analysis

When the price of penetrative sex rises, rational teenagers seek substitutes. If teenagers really did think about the consequences of their actions, they would have less risky sex if the cost of risky sex went up; people who are still having sex have switched to using birth-control methods that will also protect them from STI.

The oral-sex epidemic is a rational response to a rise in the price of penetrative sex; use of the contraceptive pill is down by nearly a fifth, but use of condoms is up by more than a third. The percentage of teenage virgins has risen by more than 15 percent since the beginning of the 1990s.

(b) Policy implication

If teenagers are rational, abortion-notification or -consent laws would discourage risky sex among teens, relative to adults.

Some scholars found that wherever and whenever such laws have been passed, gonorrhoea rates in the teenage and adult populations start to diverge. When it becomes more troublesome to get an abortion, teenagers seem to cut back on unprotected sex.

Greg Mankiw's Blog: A Few Good Readings

Fat Tax

Mankiw told before about obesity and raised two lessons:

1. People respond to incentives. When gaining weight is cheaper, people gain more weight.

2. Government policies can have unintended consequences.

How about a "fat tax" to encourage healthier eating? If we think obesity as a serious social problem, we might have to propose it.

Obesity and Economics

Economics has been said to be a study related to "monetary matter", but as once Gary Becker said, it seems more precise to me that economics is a study related to "human behavior". From this viewpoint, monetary matter could be causes and results of human behavior.

In this respect, economics could tell why people get obese(*):

When people decide to take in meal, they must compare the present benefit from eating today to the present cost of being obese tomorrow. However, when thinking about the present benefit from eating today, we have to subtract the cost (time and money spent on eating food) from the utility obtained by eating food today because we would be more likely to be obese if we could eat more meal at lower cost. The lower cost of meal would probably make us obese.

In this point, "the cost of meal" is one of the most important factors to determine obesity. From the experience of the United States, the lower the cost of taking in calorie, the more likely for people to be obese.

Regarding the present cost of being obese tomorrow, people's preference for obesity avoidance could be also related to how obese people would be, and thus how patient people are. In economics, it is named people's "time preference", "discount rate" or "ratio of patience": more impatient people are less likely to stand up their hunger because they discount more the cost of being obese tomorrow.

When we think about obesity, time preference can be a key term!

It can be derived by asking the following two questions:

(1)What rate of interest would you request 1 year later if your $100 were put in a checking account?

(2)What rate of interest would you pay 1 year later if you borrowed $100 from your friend?

Regarding the interest rate derived by asking like (1), the higher it is, the more impatient people are. That is, the more impatient people are more likely to be obese because they discount more the risk of being obese in their future. In fact, one research conducted by Osaka University tells that the more impatient people have higher BMI.

Note that BMI stands for Body Mass Index and (BMI) = (weight; kg)/(height; m)^2 and obesity tells (BMI) is more than 25. Moreover, in Japan the BMI of the men at any age and the women at elder age has been increasing for 20 years.

Also, regarding the time preference derived by asking like (2), is it the same as one that they get when they make a deposit? The time preference earned by making a deposit is reported to tend to be higher than one paid by running up a debt.

It should be natural, though. Interestingly, the larger such difference between the two interest rates, the lower the BMI people have. It could be easier to think about the reason:

We assume that "obesity" be seen as "debt" and so we can understand that we would have to pay higher interest rate(higher cost of being obese) if we accumulated a debt called "obesity".

Thus, people who don't like paying such higher interest rate are less likely to be obese.

In Japan, women are reported to be less likely to be obese than men and two reasons can be considered for this trend(**):

(1)The difference of women between the two interest rates is larger than that of men.

(2)Women are less impatient than men.

To sum up, the above study tells that "obesity" can be explained to some extent by the idea of "intertemporal choice".

[Note]

(*)The above study comes from the article written by Prof. Shinsuke Ikeda of Osaka University (in Japanese). However, it is summed up by Taro, so any mistake is due to Taro.

(**) Another reference is here.

肥満と経済学

本日大学で肥満と経済学に関するセミナーに参加した。マーキュット大学のオルガ先生の発表であったが、一見すると「肥満と経済学」って変な組み合わせに見えよう。オルガ先生の研究発表の概要はこちら（ただし英文）。

経済学は、「お金にまつわる研究領域」というのが日本の世間一般での定説（？）といえようが、小生そうは考えない。経済学は「人間行動とその社会的関わりに関する研究領域」だと考えている。

その観点から言えば、「なぜ人は太るのか？」も立派な経済学的問題といえよう。太るもやせるも、多少遺伝的な問題や健康上の問題もあろうが、個人の行動の結果ではなかろうか？

Body Fat and Income

04/18/08 Revised

Today I joined the seminar, whose guest speaker is Olga Yakusheva of Marquette University. Her research caught my eye: "The relationship between Body Fat and Income: Skinny Bodies and Thin Wallets?" It sounds interesting, doesn't it?

She uses data on over 15,000 individuals from the four most recent cohorts of the National Health and Nutrition Examination Survey (NHANES) to determine the relationship between a person's body fat (measured by Body Mass Index) and their socioeconomic status, measured by family income and examine its source.

Her study shows that obesity is most prevalent among low-income women and middle-income men, compared to other socioeconomic groups and that lower rates of obesity among upper class men and women, and lower class men, are not explained by differences in physical activity levels(in-home, at-work and at-leisure), and only marginally explained by differences in eating habits.

She says that the possibility could be pointed out that the relationship between income and body fat in the adult population has its roots in people's childhood and young adulthood experiences even though the source of the correlation between body fat and income is not fully explained.

Moreover, a more precise targeting of obesity prevention policies to specific socioeconomic groups where obesity is most prevalent.


While listening to her, I was just wondering whether there should be such studies related to Japan and other countries.

As some professors said to her in the seminar, it should be also important for such studies to look at another relationship between geography, and inheritance and body fat. However, it looks somewhat difficult to look at such relationships because of the lack of available and reliable data set.

PS

Prof. Olga emailed me later:

Dear Taro,

Thanks for your email - I found a lot of your ideas very interesting. Most definitely, doing a time-series type of analysis would be interesting, but there aren't data for that....

Olga Yakusheva
Economics Department
Marquette University