A Conversation with David Brazel on Obesity Research

                                                                   Boulder Creek (image source here)

                                                                   Boulder Creek (image source here)

In addition to the Economics Department here at the University of Colorado Boulder, where I am a professor, I have been hanging out at the Institute for Behavioral Genetics, which is on the other end of campus, a beautiful hike past the football stadium and then along the Boulder Creek Path. 

One of the impressive people I have met at the Institute for Behavior Genetics is David Brazel, currently a Predoctoral Trainee of the Institute for Behavioral Genetics and of Molecular Cellular and Developmental Biology. 

                          David Brazel

                          David Brazel

Though he now focuses on drug addiction, in order to get into his joint program, David had to do a research proposal comparable in detail to a grant proposal, which was directed at research on obesity. So David read a lot of the previous research in this area. I had a chance to talk to David last Wednesday and David graciously gave his permission for me to share with you what I learned from that conversation and the hypotheses about obesity that I ran by David. I should say that what I learned, or thought I learned, may not exactly match what David said or what he thinks. What I have below represents what I ended up thinking after talking to him. 

Leptin and Ghrelin. Following Jason Fung in the way I lay out in "Obesity Is Always and Everywhere an Insulin Phenomenon, I have emphasized the role of insulin and its opponent hormone glucagon. David said that research has also pointed to leptin and ghrelin as extremely important. For example, the genes for leptin and ghrelin seem important in predicting obesity. This is something I need to look into more. 

Beige Fat. One of the intriguing things David mentioned was that some of the most important genes for obesity have to do with whether fat cells are trying to generate heat or not. Mice have such a high surface-area to volume ratio, they would get cold if they didn't have something called "brown fat," which generates a lot of heat. Humans don't have brown fat in the same sense as rodents, but they do often have fat cells with an enhanced number of mitochondria and enhanced heat generation that are called "beige fat." 

One way to make your fat cells more beige so that they burn more energy is to live in a cold climate. It may be that taking cold showers could make a difference, too. A lot of research remains to be done on this. 

Obesity research is still at an early stage in many areas. One general theme from my conversaition with David was this: while the views I have taken about obesity on this blog might be wrong, they are consistent with the existing research on obesity. This is saying much less than you might think: the results of existing research admit of many, many interpretations, and much is simply unknown. 

Is It Healthy for Humans to Eat What Is Healthy for Rats and Mice? One simple example is my suspicion of using rodent data to give advice about what humans should eat. (Thinking about rodent brown fat might steer you in the right direction, but thinking about which foods are fattening to rodents may steer you in the wrong one.) Several people I have talked to who are involved in genetics research have been sympathetic to this argument that I made in "The Case Against Sugar: Stephan Guyenet vs. Gary Taubes":

I am inclined to agree with Stephan that rodent data do not support the idea that sugar is more harmful than fat (though it does seem to support the idea that fat plus sugar is worse than fat alone). But I am struck by the possibility that rodents might be much better adapted to highcarb diets than humans are. This may even allow them to eat sugar with less harm than humans. Am I wrong in thinking that for many, many generations rodents outside laboratories have tended to eat highcarb diets? The "many, many generations" is important. Even if rodents had only been eating highcarb diets for the same number of years as humans, the larger number of generations per century would have allowed rodents that hang around humans to be naturally selected to tolerate highcarb diets more than long-generationed humans.

Every discipline tends to develop conventions that the best research that is feasible for the typical researcher should be treated with respect. But if the best experimental research that is feasible is studies on rodents that might be much better adapted to highcarb diets than humans and small-sample-size human studies, it shouldn't make it any more persuasive to those of us who are not acculturated diet scientists for them to say "This is the state of the art."

Both Stephan Guyenet, as I discuss in "The Case Against Sugar: Stephan Guyenet vs. Gary Taubes" and Seth Yoder, as I discuss in "The Case Against the Case Against Sugar: Seth Yoder vs. Gary Taubes," are insufficiently cautious in applying rodent data to recommendations about what humans should eat. This leads me to believe that it might be common for nutritionists to rely too heavily and too uncritically on results from rodent data. 

Almost everyone would agree that the adequacy of mice and rats as a model for human nutrition is a crucial scientific question. The specific research I would love to have someone point me to, and would love to see someone pursue if it hasn't been done already is to look closely at the coevolution of mice and rats with humans, and the evolutionary response of mice and rats to the human agricultural transition. I know there has been a lot of interesting work on the coevolution of humans and dogs, so this is a type of research that can be done. There may even be mouse remains partially preserved in ancient middens that would provide some ancient mouse DNA before, during and after the human agricultural transition. 

Belly Fat. It is known that belly fat is correlated with insulin resistance. But research has not fully established why. I threw out a possibility that extends the logic of this passage from "Obesity Is Always and Everywhere an Insulin Phenomenon": 

People often talk as if obesity itself caused many chronic diseases. But other than joint problems, and the social stigma of obesity, almost all of the diseases associated with obesity could be due to the common cause of elevated insulin levels. That is,

  • chronically elevated insulin levels usually cause obesity, and

  • chronically elevated insulin levels have many dangerous side effects. 

There is an interesting theoretical case in which chronically high insulin levels would be de-linked from obesity. Suppose the fat cells of someone caught in a carb rebound cycle became resistant to insulin, but his or her muscle cells retained their normal sensitivity to insulin. Because the fat cells would not respond much to the insulin signal telling them to take in glucose from the bloodstream and convert it into triglycerides and then fat, he or she would not gain much weight. But to keep blood glucose levels in line, insulin levels would have to go up even further to get the job done just from the muscle cell response to insulin. If high insulin levels cause most of the chronic diseases we associate with obesity, then while still normal in weight, he or she would be at risk for all of these chronic diseases. This is someone others might envy for being able to eat anything without gaining weight—right up until he or she died of a heart attack. ...

If, on the other hand, muscle cells become more resistant to insulin than fat cells, then the higher insulin levels that result from insulin resistance will lead to weight gain. Moreover, the fact that even a little food can still elevate insulin levels quite a bit will make weight loss very difficult. In saying this, I have in mind this model relating insulin levels to fat accumulation and decumulation

  • high insulin level —> accumulation of body fat

  • medium insulin levels over a substantial range —> body fat steady

  • low insulin level —> fat burning

If you have insulin resistance for muscle cells but not fat cells, even small amounts of food will prevent reaching an insulin level low enough to lead to fat burning. The only way to get insulin levels low enough to lead to fat burning may be to have a substantial period of time with no food at all—fasting.  

One logical possibility for why belly fat is an especially good indicator of insulin resistance is that belly fat cells are one of the last type of fat cells to become insulin resistance. So they still respond strongly to the "take in blood sugar and turn it into fat" message of elevated insulin even when high levels of insulin shouting that message go less and less heeded by other fat cells. This is speculative, but what is known is that there are several distinct types of fat cells in the body. So it is not impossible that belly fat cells get insulin resistant at a slower rate on average than other types of fat cells. 

The Net Body Fat Accumulation Response to Insulin Curve. Talking to David, I waved my hands in the air trying to describe something like the graph below giving the picture I have in my mind of how the permanent weight gain or weight loss of fat accumulation or fat burning is related to insulin levels. Here, as in response to the other ideas I put forward, he said the basic idea was possible; the research hasn't been done to confirm or refute this idea. He also emphasized that the set of mechanisms would no doubt be more complex than this. 

I think there is a bit of optical illusion in the graph below: the horizontal axis really is flat, but a trick of the eye makes it look downward-sloping. The insulin level—really a stand-in for a linear combination of several hormones—is on the horizontal axis. Also on the horizontal axis is the equation giving where the insulin level comes from in this simplified model: the product of calories, average insulin index of the food one eats and one's level of insulin resistance. Insulin resistance increases the insulin response for any type of food. So the more insulin resistant you are, the more you need to shift to lower insulin-index foods and the more you need to fast if you want to achieve a low enough insulin level to lose weight. (See "Forget Calorie Counting; It's the Insulin Index, Stupid" on the foods to avoid and the foods to move toward to lower the average insulin index of the food you eat.) 

A key feature of the net body fat accumulation response to insulin curve that I have drawn is that it has a flat part. There is a range of insulin levels that lead to no weight gain and no weight loss. But a high enough insulin level, while it lasts, leads to weight gain; conversely, a low enough insulin level, while it lasts, leads to weight loss. A simple way to get a response curve of this shape is to have one signaling mechanism for weight gain that has a high insulin level threshold and another signaling mechanism for weight loss that has a low insulin level threshold. The main reason to think the shape might be something like this is that people are as close to steady in their weight as they are. Without a flat part to the response curve, that would be harder to get.  

It might seem that lowering calorie intake would be a good way to lower your insulin index. But calorie intake also matters for making sure your cells have enough nourishment and energy. The balance between pain and weight loss is dramatically different depending on what part of the response curve you are in:

  • At a low enough insulin level, fat is released from your fat cells and your cells will have plenty of nourishment.
  • At the right end of the flat part of the curve, your cells will also have plenty of nourishment.
  • At the left end of the flat part of the curve, you aren't eating very many calories and your body isn't burning any fat, so there is not enough nourishment for your cells. This is sometimes called cellular starvation, and it isn't pleasant. 
  • At a high enough insulin level, sugar will be taken out of your blood stream and stored as fat so fast that you are likely to feel quite hungry. It isn't exactly cellular starvation, but it is genuine hunger. 

Technically, in this simple model, the amount of nourishment available to cells is shown by which line you are on parallel to the purple line. The purple line itself can be seen as a dividing line between adequate and inadequate nourishment. What give this model its interesting results is that nourishment is linear in calories and net body fat accumulation, but net body fat accumulation is nonlinear in insulin levels. 

The bottom line is that you will feel hungry even shortly after eating a lot if you are eating a lot of high insulin index foods, but as long as you have plenty of fat to burn, you won't feel all that hungry if you are not eating anything at all. That is the revolutionary idea that I learned from reading Jason Fung's books The Obesity Code and The Complete Guide to Fastingand an idea that matches my own experience and the experience a few other people who have shared their experiences as self-appointed guinea pigs with me. 

Don't miss these other posts on fighting obesity:

Also see the last section of "Five Books That Have Changed My Life."


On Rob Porter

Image source. Rob Porter is holding the document Link to the Wikipedia article on Rob Porter

Note: This is not about the well-known economist named Rob Porter but the former White House staffer

The sharp edge of the Rob Porter story came home to me when I realized my personal connection. Other than the victims and those close to the victims, some of those whose hearts are hurt most deeply by someone's misbehavior are the parents of the bad actor. I know Rob Porter's father Roger Porter well. 

My connection comes through the small world of Mormons at the highest levels of academia. Roger Porter was my bishop when I was in the student congregation in Cambridge, Massachusetts in 1977-1979 before I served a Mormon mission in Japan. Moreover, in a Mormon congregation, even the bishop and his family has a "home teacher" (see "Inside Mormonism: The Home Teachers Come Over"), and although I was less than 19 years old during this period, I was assigned as the home teacher for Roger Porter and his family. (Since Rob was born in 1977, that means I was the home teacher for Rob Porter during his first two years of life.)

Roger Porter is a truly delightful person. His his wife Ann was also truly delightful. Ann died last year and so was spared the latest reminder of Rob's bad behavior. I don't see any angle whereby Rob could make any progress at blaming his parents for his bad actions. 

Tangentially, as a young White House Fellow, Roger Porter took on a role in the Ford Administration similar to role that Rob took in the Trump administration: being an effective manager of the paper flow. 

Good parents want their children to be good and to do good as well as to be happy. By all accounts, Rob was doing some good within the Trump Administration; but he did bad things in his marriages.

I am moved by the progress that the #MeToo era represents. It is a huge step forward for humanity to the extent that it is now harder for men to get away with treating women badly.

The question I have, though, is what the path for repentance is for men who have treated women badly. One thing I think is a minimum standard for us as a public to treat men in the public sphere as having repented is this: men who have done serious harm to women should come forward and admit their crimes and near-crimes without waiting to be accused by others. If someone proactively says they have acted badly and shows real evidence of having turned over a new leaf, there should be some length of time after which we as a public should treat them more or less the same as those who were never bad in the first place. (In the private sphere, more caution is likely to be appropriate for women.) 

The Mormon Church, in particular, should encourage men who have treated women badly to talk about what they did wrong and their efforts to do better. This sends an important to other men about intolerable behavior. The Mormon Church is an institution that could dramatically improve the record of its men in their treatment of its women by having men who are truly remorseful talk about how they mistreated women and how terrible a thing that is. (Other institutions need this just as much, but have less of the institutional capability to make it happen.)

Marriage—Not for the Faint of Heart

                                     Miles and Gail in 1984 (engagement photo)

                                     Miles and Gail in 1984 (engagement photo)

I am proud to share with you the first guest post on supplysideliberal.com by my wife Gail. It is also the 2d post on her blog resilienceconspiracy.com

This is a Valentine's Day themed post. In case you are interested, I have two Valentine's Day themed posts of my own: "Marriage 101" and "Marriage 102."

Below are Gail's words:

When I was 22 years old, I met Miles Kimball.  Two months later we were married. We were young, attracted to one another, and had an uninformed confidence born of youth and optimism that we could make a successful marriage. 

When I looked into Miles’s eyes, I thought about all the wonderful things in our future: kids, jobs, and building a life together that would be fulfilling and joyful.  I imagined the love I felt for him would naturally grow, with no thought of the real work a successful marriage requires.

I’ve sometimes wondered if I could have seen the challenges ahead, would I have entered into this partnership?  If I could have seen the grief, heartache, and work it would take to find common ground . . . would I have gazed into this man’s eyes and agreed to spend my life with him?

Miles and I have been married 33½ years.  We’ve had the tragic misfortune of burying three children—each separate loss taking a tremendous toll on our family.  We’ve regrouped many times, struggling to find the language to explain our separate experiences in order to move on together. 

Romantic love is fun and mostly easy.  This Valentine’s Day I’d like to pay tribute to the troopers, the couples who manage to sort through all the challenges, upheavals, job losses, grief, health challenges and more . . . and still manage to connect, eye-to-eye with the person they long-ago promised to spend their life with.

Love is complicated . . . and sometimes very simple.  I remember the first time I saw Miles walking toward me to pick me up for our first date.  I felt a surge of hope and wonder.  Now when Miles walks toward me I feel the validation of someone who sees me, has comforted me, and has shouldered our shared burdens with grace and humor.  After all we’ve been through, he continues to approach life with a happiness and optimism I’ve come to rely on. 

Today, Miles and I still want to be in the same room with one another and face whatever is coming together.  Who could ask for more?

The Heavy Non-Health Consequences of Heaviness

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                                                  Link to the article above

                                                  Link to the article above

Obesity has many other negative consequences in our culture beyond its negative health consequences. The introduction to Shoshana Grossbard and Sankar Mukhopadhyay's article flagged above lists many:

Obesity is a major problem in the industrialized world, including the US. Its health and health cost consequences have been well documented, e.g., in Strum (2002) and Cawley and Meyerhoefer (2012). In addition, higher body weight may have negative social and economic consequences. Several studies (Register and Williams 1990; Averett and Korenman 1996; Pagan and Davila 1997; Cawley 2004; Atella et al. 2008; Johar and Katayama 2012; Cawley and Meyerhoefer 2012; Sabia and Rees 2012; Larose et al. 2016 among others) have found an inverse relationship between women’s earnings and their body weight. There is a related but smaller literature that explores the effects of BMI on employment status. Lindeboom et al. (2010) do not find any significant effect of obesity on employment in the UK. Morris (2007) on the other hand finds that obese women are less likely to participate in the labor market in the UK. Two experimental studies, Rooth (2009) and Reichert (2015), find a negative effect of BMI on employment. Caliendo and Gehrsitz (2016) provide semiparametric estimates for the relationship between BMI and employment and find evidence of non-linearity.

Furthermore, body weight has negative consequences for a number of outcomes related to couple formation. It reduces (1) women’s dating and matching opportunities (Lemennicier 1988, Hitsch et al. 2010, Vaillant and Wolff 2011; Chiappori 1992), (2) their likelihood of cohabitation and marriage (Mukhopadhyay 2008) but not in a linear way (Malcolm and Kaya 2016), and (3) a wife’s relative influence on how the couple’s resources are internally distributed (Oreffice and Quintana-Domeque 2012). Singles with higher BMI may expect less from marriage. For instance, Vaillant and Wolff (2011) show that French obese women are less likely to expect men to be tall and charming and are more willing to accept a violent mate. Obese women are also less likely to be married to men with higher income and education (Oreffice and Quintana-Domeque 2010).

The research behind their article identifies another, as described in the abstract:

Is BMI related to hours of work through marriage market mechanisms? We empirically explore this issue using data from the NLSY79 and NLSY97 and a number of estimation strategies (including OLS, IV, and sibling FE). Our IV estimates (with same-sex sibling’s BMI as an instrument and a large set of controls including wage) suggest that a one-unit increase in BMI leads to an almost 2% increase in White married women’s hours of work. However, BMI is not associated with hours of work of married men. We also find that a one-unit increase in BMI leads to a 1.4% increase in White single women’s hours of work, suggesting that single women may expect future in-marriage transfers that vary by body weight. We show that the positive association between BMI and hours of work of White single women increases with self-assessed probability of future marriage and varies with expected cumulative spousal income. Comparisons between the association between BMI and hours of work for White and Black married women suggest a possible racial gap in intra-marriage transfers from husbands to wives.

Moreover, beyond all the negative consequences listed above, I am struck by what a great share of the consciousness of many people is filled by thoughts about their own unsuccessful weight-loss efforts. That is, these negative consequences of obesity and being overweight are on top of the costs people incur to try to weigh less. I emphasize the expenditure of consciousness itself, but of course there is a great deal of time and money spent in weight-loss efforts as well. It is a bit like crime: we suffer from crime and we are hurt by all of the costs we incur to try to reduce crime.  

Having emphasized all the costs on top of the health cost, how big is the health cost itself? Here is a way to get an idea of the right order of magnitude. A little googling turns up the 2013 PLOS One article "Life Years Lost Associated with Obesity-Related Diseases for U.S. Non-Smoking Adults" by Su-Hsin Chang , Lisa M. Pollack, Graham A. Colditz which cites these CDC figures in the introduction:

The Centers for Disease Control and Prevention (CDC) estimates that approximately 112,000 deaths are associated with obesity each year in the United States [6][7].

When combined with a $9 million valuation of a statistical life, which is not an unreasonable number (see the Wikipedia article "Value of Life"), that comes to slightly over $1 trillion worth of obesity-related deaths each year

The total cost of obesity, including all of the above, motivates me to keep writing about how to fight it. Here are the main posts I have written so far on fighting obesity:

Also see the last section of "Five Books That Have Changed My Life."

John Locke: Thinking of Mothers and Fathers On a Par Undercuts a Misleading Autocratic Metaphor

Large-scale matriarchies appear often in fiction, but are hard to point to in real life. Some of these fictions project matriarchy into prehistory. But I suspect the status of women relative to men is better now than at any other time since the emergence of Homo Sapiens. For better than now, we need to look to the future, not the past.

Large-scale matriarchies appear often in fiction, but are hard to point to in real life. Some of these fictions project matriarchy into prehistory. But I suspect the status of women relative to men is better now than at any other time since the emergence of Homo Sapiens. For better than now, we need to look to the future, not the past.

The word "patriarchy" points to a very real correlation between autocratic hierarchy and sexism. There are, and there have been female dictators and semi-dictators. But it is hard to come up with an example of an autocratic government that has as high a percentage of women in the top echelons of power (say in a list of the top 100 most politically powerful people in a nation) as many democracies do. (Communist governments officially proclaimed the equality of men and women. But they did not and do not have a large percentage of women in the top echelons of power.)

In sections 52 and 53 of John Locke's 2d Treatise on Government: “Of Civil Government” (Chapter VI. Of Paternal Power), John Locke points to an interesting reason that gender equality is a bad fit for autocracy: it put two people at the head of each family, instead of one, and thereby undercuts the notion that one person needs to be at the top of society:

It may perhaps be censured as an impertinent criticism, in a discourse of this nature, to find fault with words and names, that have obtained in the world: and yet possibly it may not be amiss to offer new ones, when the old are apt to lead men into mistakes, as this of paternal power probably has done, which seems so to place the power of parents over their children wholly in the father, as if the mother had no share in it; whereas, if we consult reason or revelation, we shall find, she hath an equal title. This may give one reason to ask, whether this might not be more properly called parental power? for whatever obligation nature and the right of generation lays on children, it must certainly bind them equal to both the concurrent causes of it. And accordingly we see the positive law of God every where joins them together, without distinction, when it commands the obedience of children, “Honour thy father and thy mother,” Exod. xx. 12. “Whosoever curseth his father or his mother,” Lev. xx. 9. “Ye shall fear every man his mother and his father,” Lev. xix. 3. “Children, obey your parents,” &c. Eph. vi. 1. is the style of the Old and New Testament.  1

 Had but this one thing been well considered, without looking any deeper into the matter, it might perhaps have kept men from running into those gross mistakes, they have made, about this power of parents; which, however it might, without any great harshness, bear the name of absolute dominion, and regal authority, when under the title of paternal power it seemed appropriated to the father, would yet have sounded but oddly, and in the very name shewn the absurdity, if this supposed absolute power over children had been called parental; and thereby have discovered, that it belonged to the mother too: for it will but very ill serve the turn of those men, who contend so much for the absolute power and authority of the fatherhood, as they call it, that the mother should have any share in it; and it would have but ill supported the monarchy they contend for, when by the very name it appeared, that that fundamental authority, from whence they would derive their government of a single person only, was not placed in one, but two persons jointly. But to let this of names pass.

The image of mothers and fathers being equal leaders of a family is not even a good fit as an image for oligarchic rule: most mother-father pairs leading families jointly have dispositions that differ more than the three individuals in a triumvirate, for example. So the image of mothers and fathers leading families jointly tends to suggest the idea that it is possible for people who are different to be involved in ruling. That is at least partway toward the idea of democracy. 

I have become enamored of the idea that involving people with different dispositions and different views in making a decision is likely to result in a better decision. Believing this forces me into the awkward position of being open to the possibility that I might be wrong even in situations where I am convinced that I am right. It also leads me to hope that my words persuade when I am right and don't persuade when (unbeknownst to me) I am wrong. 

I have enough confidence in my own views that if somehow, I were magically in the position of being a benevolent dictator in a society that would tolerate a departure from democracy, it would be hard to lay down that power entirely. But one of the first things I would do would be to gather around me a set of councillors I respected and trusted who would not hesitate to tell me when they thought I was wrong. Then I would irrevocably cede constitutional authority to the council that I had appointed—and mandate a transition to democracy by the time most of those councillors would become unable to serve due to death or advanced age. 


For links to other John Locke posts, see the John Locke aggregator posts: 

Most of the Gender Wage Gap Stems from Inequality in the Household, Inequality in the Culture, and Hostile Workplaces

In this video, Christina Hoff Sommers recounts the standard result that after accounting for differences occupational choices, there isn't much of a gender gap left. She note that there are also plenty of omitted variables in the typical study to potentially account for most of the rest. 

Christina also emphasizes the market logic that could lead to such a result: if women are cheaper, a private equity firm could make a lot of money by taking over firms that are slowly losing money and make them profitable just by hiring cheaper women. They could cut wages and still get plenty of employees simply by being willing to hire mostly women. Somewhat harder, entrepreneurs willing to hire mostly women should often be successful against established businesses that are reluctant to hire women. I had a storify discussion about this: "The Argument that the Free Market Will Rectify Discrimination as a Guide to Business Opportunities.

Let me say something about these two points in reverse order.

The logic that predicts the profit motive is enough to close the gender wage gap does not operate in areas where the profit motive is weak. This means that a good place to look for genuine gender wage gaps is in the nonprofit sector—for example, in nonprofit universities. Even there, cost-minimization in the hiring of lower staff is likely to suppress genuine gender wage gaps for lower-level staff. The genuine gender wage gaps are more likely to be concentrated among the professoriate. This does present a genuine opportunity for universities that hire more female professors. But it is not easy for private equity firms to take over a university and make it follow a policy of hiring more female professors. Nor is it easy to establish successful new universities that can compete at the top rank. So universities themselves need to decide to seize the opportunity if it is going to happen; it is not likely to be forced on them. (On this opportunity for Economics Departments specifically, see my post "When Women Don’t Get Any Credit for Coauthoring with Men.")

Turning to Christina's research summary suggesting their is very little in the way of a genuine gender wage gap, I am struck first by how many of the differences in occupational choices made by men and women to back to inequality within households headed by a male-female pair. In this list, let me use the terminology "husband" and "wife," with the understanding that similar issues applied to unmarried heterosexual couples:

  1. Husbands are less willing to relocate to help out their wives' careers than wives are to help out their husband's careers. 
  2. When there are children, more of the childcare duties typically fall on the wives than the husbands. In particular, being "on-call" for unpredictable child-related events such as a kid getting sick tends to fall more on wives than on husbands. Both regular childcare duties and being "on-call" for unpredictable child-related events make it more difficult to work long hours and more difficult to be "on-call" for an employer. 

Second, I am struck by the role of sometimes subtly, sometimes not-so-subtly hostile workplaces in discouraging women from pursuing many lucrative professions. For example, think of Christina's list of high-paying careers in which women are underrepresented:

  • Petroleum Engineering
  • Math and Computer Sciences
  • Aerospace Engineering
  • Chemical Engineering

I am willing to bet that women face ill-treatment in all of these fields. What I know best is that Silicon Valley has produced many stories of ill-treatment for women in the tech industry. In math, the discouragement of women begins early in telling them they are not good at math and sciences. On this, see "Calculus is Hard. Women Are More Likely to Think That Means They’re Not Smart Enough for Science, Technology, Engineering and Math" and "There's One Key Difference Between Kids Who Excel at Math and Those Who Don't." 

In addition to outright ill-treatment, a common type of discrimination against women comes from workplace cultures that amp up the need for highly "competitive" self-serving behaviors that our culture has more actively socialized women against doing than it has socialized men against doing. Men also take advantage of prosocial things that women have been socialized towards doing. 

The details differ by particular occupation. To see how this places out in a narrow neck of the woods, see "How Big is the Sexism Problem in Economics?

When men create hostile or unfair workplaces for women, there can be a tipping point where private equity firms and entrepreneurs swoop in and switch to workplaces with such a preponderance of women that the few men are unable to enforce a hostile workplace environment. But this can require a very discontinuous change. A few more women and a few less men won't do it. There are market opportunities here, but only for the bold.

Third, I do think that our culture bestows more approval on women who sacrifice salary for nonpecuniary benefits than on men who sacrifice salary for nonpecuniary benefits. Men who choose a low-paid meaningful job are more likely to face criticism than women are for not sucking it up and taking the alternative soul-deadening job in order to better support the family. Leaving anything related to child-rearing in another category (see above), here are some of the other nonpecuniary benefits women are given more social approval than men for choosing even at the cost of low pay:

  • the knowledge that one is making the world a better place with one's job
  • the knowledge that one is greatly helping particular individuals with one's job
  • satisfying interpersonal interactions on the job with either coworkers or customers/clients
  • an artistic element to a job
  • physical safety

Looking at another, more complex dimension, both men and women are given more social approval for choosing jobs that seem gender appropriate. This cuts in all kinds of ways on the relative pay of men and women. For example, men may be too slow to leave the declining manufacturing sector for mid-level and low-level healthcare positions because a factory job seems more masculine. Here women are helped by the fact that nursing, which is a relative good career compared to factory work (given the way things are going), has been deemed gender-appropriate for women. On the other hand, women may be especially ready to go into elementary school teaching despite its low pay because even in 2018, this seems like an especially gender-appropriate career. 

Conclusion: The bottom line is this:

  1. There are opportunities to do well by doing good in rectifying inequality in the workplace between men and women, but they may take insight and courage.
  2. In addition to its direct harm, men behaving badly to women can be part of the source of pay differences. Better behavior is called for. It is great to see the dam break that guarded a cesspool of sexual assault and harrassment as the #MeToo moment continues with strength. Beyond that, there are a few words recommending better behavior in my post "On Being a Good Guy." 
  3. The personal is economic. If husbands won't relocate for the sake of their wives' careers and won't take on tougher childcare duties, it puts women behind in the workplace.
  4. Just because most employers aren't discriminating in the purest sense of discrimination doesn't mean that things are fair.  


Hat tip to Joseph Kimball for pointing me to this video. 



Julia Rohrer on the Selection Distortion Effect—That Weird Third Variable Problem: Conditioning on a Collider

I really like this blog post.

Here is how I stumbled across it. When I suggested that correlations being caused by a third factor needed a snappier, catchier name in "Cousin Causality," Chris Chabris tweeted that it was called "third-variable causation" in psychology. Though neither this nor the other term in use, "shared causation", meet my standards for being snappy and catchy, knowing the phrase "third-variable causation" led me to a search on Twitter that turned up Julia Rohrer's post.  

Diseases of Civilization

In "Obesity Is Always and Everywhere an Insulin Phenomenon" I quote Gary Taubes at some length about the dramatically higher incidence of diseases such as heart disease, cancer, diabetes, etc. in countries with a modern diet and lifestyle. But having realized from reading Seth Yoder's devastating post how unreliable a reporter Gary Taubes is, as I detailed in "The Case Against the Case Against Sugar: Seth Yoder vs. Gary Taubes, I wanted to document that while various authors disagree about the causes of what are variously called the "Diseases of Civilization," "Western Diseases" and "Diseases of Affluence," there is broad agreement about the fact that these diseases are rare among less affluent groups with longstanding indigenous diets and lifestyles.  

Let me start with some passages from The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet by Nina Teicholz. Nina's main concern is to exonerate dietary fat and animal food more generally as the causes of the Diseases of Civilization. After beginning Chapter 1 by talking about Inuit's meat-heavy diet, Nina turns other groups (I have added the group names in bold as subheadings):

The Masai and Samburus: Across the globe half a century later, George V. Mann, a doctor and professor of biochemistry who had traveled to Africa, had a similarly counterintuitive experience. Although his colleagues in the United States were lining up in support of an increasingly popular hypothesis that animal fats cause heart disease, in Africa Mann was seeing a totally different reality. He and his team from Vanderbilt University took a mobile laboratory to Kenya in the early 1960s in order to study the Masai people. Mann had heard that the Masai men ate nothing but meat, blood, and milk—a diet, like the Inuits’, comprised of almost entirely animal fat—and that they considered fruits and vegetables fit to be eaten only by cows.

Mann was building upon the work of A. Gerald Shaper, a South African doctor working at a university in Uganda, who had traveled farther north to study a similar tribe—the Samburus. A young Samburu man would drink from 2 to 7 liters of milk each day, depending on the season, which worked out on average to well over a pound of butterfat. His cholesterol intake was sky-high, especially during periods when he would add 2 to 4 pounds of meat to his daily diet of milk. Mann found the same with the Masai: the warriors drank 3 to 5 liters of milk daily, usually in two meals. When milk ran low in the dry season, they would mix it with cow blood. Not shirking the meat, they ate lamb, goat, and beef regularly, and on special occasions or on market days, when cattle were killed, they would eat 4 to 10 pounds of fatty beef per person. For both tribes, fat was the source of more than 60 percent of their calories, and all of it came from animal sources, which meant that it was largely saturated. For the young men of the warrior (“murran”) class, Mann reported that “no vegetable products are taken.”

Despite all of this, the blood pressure and weight of both these Masai and the Samburu peoples were about 50 percent lower than their American counterparts—and, most significantly, these numbers did not rise with age. “These findings hit me very hard,” said Shaper, because they forced him to realize that it was not biologically normal for cholesterol, blood pressure, and other indicators of good health automatically to worsen with aging, as everyone in the United States assumed. In fact, a review of some twenty-six papers on various ethnic and social groups concluded that in relatively small homogenous populations living under primitive conditions, “more or less undisturbed by their contacts with civilization,” an increase in blood pressure was not part of the normal aging process. Was it possible that we in the Western world were the anomaly, driving up our blood pressure and generally ruining our health by some aspect of our diet or modern way of life?

True, the Masai were free from the kind of emotional and competitive stresses that gnaw away at the citizens of more “civilized” countries and which some people believe contribute to heart disease. The Masai also got more exercise than desk-bound Westerners: these tall, slender shepherds would walk for many miles each day with their cattle, searching for food and water. Mann thought that perhaps all this exercise might be protecting the Masai from heart disease.II But he also acknowledged that subsistence was “easy” and “labor light,” and that the elders, who “seem sedentary,” were not dying from heart attacks, either.

If our current belief about animal fat is correct, then all the meat and dairy these tribesmen were eating would have caused an epidemic of heart disease in Kenya. However, Mann found exactly the opposite—he could identify almost no heart disease at all. He documented this by performing electrocardiograms on four hundred of the men, among whom he found no evidence of a heart attack. (Shaper did the same test on one hundred of the Samburu and found “possible” signs of heart disease in only two cases.) Mann then performed autopsies on fifty Masai men and found only one case with “unequivocal” evidence of an infarction. Nor did the Masai suffer from other chronic diseases, such as cancer or diabetes. ...

The Sikhs and the Hunzas: In the early 1900s, for instance, Sir Robert McCarrison, the British government’s director of nutrition research in the Indian Medical Service and perhaps the most influential nutritionist of the first half of the twentieth century, wrote that he was “deeply impressed by the health and vigour of certain races there. The Sikhs and the Hunzas,” notably, suffered from “none of the major diseases of Western nations such as cancer, peptic ulcer, appendicitis, and dental decay.” These Indians in the north were generally long-lived and had “good physique[s],” and their vibrant health stood “in marked contrast” to the high morbidity of other groups in the southern part of India who ate mainly white rice with minimal dairy or meat. McCarrison believed he could rule out causes other than nutrition for these differences, because he found that he could reproduce a similar degree of ill-health when feeding experimental rats a diet low in milk and meat. The healthy people McCarrison observed ate some meat but mostly “an abundance” of milk and milk products such as butter and cheese, which meant that the fat content of their diet was mainly saturated.

Native Americans of the Southwest between 1898 and 1905: Meanwhile, the Native Americans of the Southwest were observed between 1898 and 1905 by the physician-turned-anthropologist Aleš Hrdlička, who wrote up his observations in a 460-page report for the Smithsonian Institute. The elders among the Native Americans he visited would likely have been raised on a diet of predominantly meat, mainly from buffalo until losing their traditional way of life, yet, as Hrdlička observed, they seemed to be spectacularly healthy and lived to a ripe old age. The incidence of centenarians among these Native Americans was, according to the 1900 US Census, 224 per million men and 254 per million women, compared to only 3 and 6 per million among men and women in the white population. Although Hrdlička noted that these numbers were probably not wholly accurate, he wrote that “no error could account for the extreme disproportion of centenarians observed.” Among the elderly he met of age ninety and up, “not one of these was either much demented or helpless.”

Hrdlička was further struck by the complete absence of chronic disease among the entire Indian population he saw. “Malignant diseases,” he wrote, “if they exist at all—that they do would be difficult to doubt—must be extremely rare.” He was told of “tumors” and saw several cases of the fibroid variety, but never came across a clear case of any other kind of tumor, nor any cancer. Hrdlička wrote that he saw only three cases of heart disease among more than two thousand Native Americans examined, and “not one pronounced instance” of atherosclerosis (buildup of plaque in the arteries). Varicose veins were rare. Nor did he observe cases of appendicitis, peritonitis, ulcer of the stomach, nor any “grave disease” of the liver. Although we cannot assume that meat eating was responsible for their good health and long life, it would be logical to conclude that a dependence on meat in no way impaired good health.

Colonial Africa and Asia: In Africa and Asia, explorers, colonialists, and missionaries in the early twentieth century were repeatedly struck by the absence of degenerative disease among isolated populations they encountered. The British Medical Journal routinely carried reports from colonial physicians who, though experienced in diagnosing cancer at home, could find very little of it in the African colonies overseas. So few cases could be identified that “some seem to assume that it does not exist,” wrote George Prentice, a physician who worked in Southern Central Africa, in 1923. Yet if there were a “relative immunity to cancer” it could not be attributed to the lack of meat in the diet ...

Gary Taubes claims that the Diseases of Civilization were brought on by the consumption of sugar and white flour. T. Colin Campbell and Thomas M. Campbell II claim that the Diseases of Civilization are caused primarily by the consumption of animal protein in their book The China Study. (See "Meat Is Amazingly Nutritious—But Is It Amazingly Nutritious for Cancer Cells, Too?") Here is their description of the Diseases of Civilization:

It doesn’t take a scientist to figure out that the possibility of death has been holding pretty steady at 100% for quite some time. There’s only one thing that we have to do in life, and that is to die. I have often met people who use this fact to justify their ambivalence toward health information. But I take a different view. I have never pursued health hoping for immortality. Good health is about being able to fully enjoy the time we do have. It is about being as functional as possible throughout our entire lives and avoiding disabling, painful, and lengthy battles with disease. There are many better ways to die, and to live.

Because the China Cancer Atlas had mortality rates for more than four dozen different kinds of disease, we had a rare opportunity to study the many ways that people die. We wondered: Do certain diseases tend to cluster in certain areas of the country? For example, did colon cancer occur in the same regions as diabetes? If this proved to be the case, we could assume that diabetes and colon cancer (or other diseases that clustered) shared common causes. These causes could include a variety of possibilities, ranging from the geographic and environmental to the biological. However, because all diseases are biological processes (gone awry), we can assume that whatever “causes” are observed, they will eventually operate through biological events.

When these diseases were cross-listed in a way that allowed every disease rate to be compared with every other disease rate,11 two groups of diseases emerged: those typically found in more economically developed areas (diseases of affluence) and those typically found in rural agricultural areas (diseases of poverty)12 (Chart 4.4).

The diseases shown in Chart 4.4 tend to be associated with diseases in their own list but not in the opposite list. A region in rural China that has a high rate of pneumonia, for example, will not have a high rate of breast cancer, but will have a high rate of a parasitic disease. The disease that kills most Westerners, coronary heart disease, is more common in areas where breast cancer also is more common. Coronary heart disease, by the way, is relatively uncommon in many developing societies of the world. This is not because people die at a younger age, thus avoiding these Western diseases. These comparisons are age-standardized rates, meaning that people of the same age are being compared.

Chart 4.4: Disease Groupings Observed in Rural China

  • Disease of Affluence (Nutritional extravagance)   Cancer (colon, lung, breast, leukemia, childhood brain, stomach, liver), diabetes, coronary heart disease  
  • Disease of Poverty (Nutritional inadequacy and poor sanitation)   Pneumonia, intestinal obstruction, peptic ulcer, digestive disease, pulmonary tuberculosis, parasitic disease, rheumatic heart disease, metabolic and endocrine disease other than diabetes, diseases of pregnancy, and many others


Disease associations of this kind have been known for quite some time in the United States and other Western countries die from diseases of affluence. For this reason, these diseases are often referred to as Western diseases. Some rural counties had few diseases of affluence while other counties had far more. The core question of the China Study was this: Is it because of differences in dietary habits? [pp. 65, 66]


To give a couple of examples at the time of our study, the death rate from coronary heart disease was seventeen times higher among American men than rural Chinese men.16 The American death rate from breast cancer was five times higher than the rural Chinese rate. Even more remarkable were the extraordinarily low rates of coronary heart disease in the southwestern Chinese provinces of Sichuan and Guizhou. During a three-year observation period (1973–1975), not one single person died of coronary heart disease before the age of sixty-four, among 246,000 men in a Guizhou county and 181,000 women in a Sichuan county!17 After these low cholesterol data were made public, I learned from three very prominent heart disease researchers and physicians, Drs. Bill Castelli, Bill Roberts, and Caldwell Esselstyn, Jr., that in their long careers they had never seen a heart disease fatality among their patients who had blood cholesterol levels below 150 mg/dL. Dr. Castelli was the long-time director of the famous Framingham Heart Study of NIH; Dr. Esselstyn was a renowned surgeon at the Cleveland Clinic who did a remarkable study on reversing heart disease (chapter five); and Dr. Roberts has long been editor of the prestigious medical journal Cardiology. [p. 69]

My hero Jason Fung is a proponent of lowcarb diets, and would be sympathetic to the recommendations I make in "Forget Calorie Counting; It's the Insulin Index, Stupid," but in the following passage, he points to processed foods as a major cause of the Diseases of Civilization:

Humans evolved to eat a wide range of foods without detrimental health consequences. The Inuit peoples traditionally ate diets extremely high in animal products, which means high percentages of fat and protein. Others, such as the Okinawans, ate a traditional diet based on root vegetables, which means it’s high in carbohydrates. But both populations traditionally did not suffer metabolic diseases. These only appeared with the increasing Westernization of their diets. What humans haven’t evolved to eat are highly processed foods. During processing, the natural balance of macronutrients, fiber, and micronutrients is completely disrupted. For example, processing the wheat berry to remove all the fat and protein means that the result, white flour, is almost pure carbohydrates. Wheat berries are natural; white flour is not. It is also ground to an extremely fine consistency that greatly speeds the absorption of carbohydrates into the bloodstream. Most other processed grains suffer the same problems. Our body has evolved to handle natural foods, and when we feed it unnatural ones, the result is illness.

Thus, while there is no agreement about what aspect of the modern diet is most to blame for the Diseases of Civilization, there is something about the modern diet and lifestyle that is causing trouble. 


Don't miss these other posts on diet and health:

Also see the last section of "Five Books That Have Changed My Life."


Charles Murray on Taking Religion Seriously

Charles Murray has an advice book: The Curmudgeon's Guide to Getting Ahead: Dos and Don'ts of Right Behavior, Tough Thinking, Clear Writing, and Living a Good Life.  It sets down the kind of advice he gave to young staffers at work. The Wall Street Journal piece flagged above is his teaser for the book. (It appeared on March 30, 2014.)

Charles's five points are:

  1. Consider Marrying Young [in your 20s instead of in your 30s]
  2. Learn How to Recognize Your Soul Mate
  3. Eventually Stop Fretting About Fame and Fortune
  4. Take Religion Seriously
  5. Watch 'Groundhog Day' Repeatedly

I like all of his advice in this essay. Here, in this post, let me focus on the 4th point: taking religion seriously. 

After letting off the hook anyone who is already seriously engaged with religion, Charles defines his audience for this section:

Now that we're alone, here's where a lot of you stand when it comes to religion: It isn't for you. You don't mind if other people are devout, but you don't get it. Smart people don't believe that stuff anymore.

After an account of how he finally came to take religion seriously (though he is still an agnostic). Charles describes what it means to take religion seriously:  

Taking religion seriously means work. If you're waiting for a road-to-Damascus experience, you're kidding yourself. Getting inside the wisdom of the great religions doesn't happen by sitting on beaches, watching sunsets and waiting for enlightenment. It can easily require as much intellectual effort as a law degree.

Even dabbling at the edges has demonstrated to me the depths of Judaism, Buddhism and Taoism. I assume that I would find similar depths in Islam and Hinduism as well. I certainly have developed a far greater appreciation for Christianity, the tradition with which I'm most familiar. The Sunday school stories I learned as a child bear no resemblance to Christianity taken seriously. You've got to grapple with the real thing.

To begin becoming more reflective, he recommends reading both religious literature and modern cosmology: "The universe isn't only stranger than we knew; it is stranger and vastly more unlikely than we could have imagined, and we aren't even close to discovering its last mysteries." As an even bigger step toward taking religion seriously: 

Find ways to put yourself around people who are profoundly religious. You will encounter individuals whose intelligence, judgment and critical faculties are as impressive as those of your smartest atheist friends—and who also possess a disquieting confidence in an underlying reality behind the many religious dogmas.

In "Five Books That Have Changed My Life" I give a thumbnail sketch of my experience being a Mormon for the first 40 years of my life. I am glad I am not a Mormon now. But I gained a great deal from having been a Mormon. I do take religion seriously. I know how deep religious feelings, religious motivations, and religious insights can be. I hope the every-other-week religion posts I have been putting up since soon after I began blogging are of some help to others—especially those who, like me, are nonsupernaturalists—in getting some inkling of the depths of religion. 

Gauti Eggertsson, Ragnar Juelsrud and Ella Getz Wold: Are Negative Nominal Interest Rates Expansionary?

It is great to see people doing formal modeling of negative interest rate policy. And it is especially good to see work of this type by a team including Gauti Eggertsson, whose research I wrote so highly of in my post "Pro Gauti Eggertsson." I wish I knew Gauti's coauthors, Ragnar Juelsrud and Ella Getz Wold better. Since this was originally posted, I have corresponded with them. Ragnar sent me this link to an ungated version of the paper

One of the most remarkable things about this paper is that instead of saying that the lower bound on interest rates is inevitable it explicitly bills itself as showing why the lower bound on interest rates needs to be removed. On pages 5 and 6, Gauti, Ragnar and Ella write this:

There is a older literature however, dating at least back to the work of Silvio Gesell more than a hundred years ago (Gesell, 1916), which contemplates more radical monetary policy regime changes than we do here. This literature has been rapidly growing in recent years. In our model, the storage cost of money, and hence the lower bound, is treated as fixed. However, policy reforms can potentially alter the lower bound or even remove it completely. An example of such policies is a direct tax on paper currency, as proposed first by Gesell and discussed in detail by Goodfriend (2000) and Buiter and Panigirtzoglou (2003). This scheme directly affects the storage cost of money, and thereby the lower bound on deposits which we derive in our model. Another possibility is abolishing paper currency altogether. This policy is discussed, among others, in Agarwal and Kimball (2015), Rogoff (2017c) and Rogoff (2017a), who also suggest more elaborate policy regimes to circumvent the ZLB. An example of such a regime is creating a system in which paper currency and electronic currency trade at different exchange rates. The results presented here should not be considered as rebuffing any of these ideas. Rather, we are simply pointing out that under the current institutional framework, empirical evidence and a stylized variation of the standard New Keynesian model do not seem to support the idea that a negative interest rate policy is an effective tool to stimulate aggregate demand. This should, in fact, be read as a motivation to study further more radical proposals such as those presented by Gesell over a century ago and more recently in the work of authors such as Goodfriend (2000), Buiter and Panigirtzoglou (2003), Rogoff (2017c) and Agarwal and Kimball (2015). In the discussion section we comment upon how our model can be extended to explore further some of these ideas, which we consider to be natural extensions.

Gauti, Ragnar and Ella return to this theme on page 33, near the end of the main body of the working paper:

In our model exercise, the storage cost of money was held fix. However, one could allow the storage cost of money - and therefore the lower bound on the deposit rate - to depend on policy. One way of making negative negative rates be expansionary, which is consistent with our account, is if the government takes actions to increase the cost of holding paper money. There are several ways in which this can be done. The oldest example is a tax on currency, as outlined by Gesell (1916). Gesell’s idea would show up as a direct reduction in the bound on the deposit rate in our model, thus giving the central bank more room to lower the interest rate on reserves - and the funding costs of banks. Another possibility is to ban higher denomination bills, a proposal discussed in among others Rogoff (2017c). To the extent that this would increase the storage cost of money, this too, should reduce the bound on the banks deposit rate. An even more radical idea, which would require some extensions to our model, is to let the reserve currency and the paper currency trade at different values. This proposal would imply an exchange rate between electronic money and paper money, and is discussed in Agarwal and Kimball (2015), Rogoff (2017a) and Rogoff (2017b). A key pillar of the proposal – but perhaps also a challenge to implementability – is that it is the reserve currency which is the economy wide unit of account by which taxes are paid, and accordingly what matters for firm price setting. If such an institutional arrangement is achieved, then there is nothing that prevents a negative interest rate on the reserve currency while cash in circulation would be traded at a different price, given by an arbitrage condition. We do not attempt to incorporate this extension to our model, but note that it seems relatively straightforward, and has the potential of solving the ZLB problem. Indeed, the take-away from the paper should not be that negative nominal rate are always non-expansionary, simply that they are predicted to be so under the current institutional arrangement. This gives all the more reason to contemplate departures from the current framework, such as those mentioned briefly here and discussed in detail by the given authors.

My post that most directly expresses this point is "If a Central Bank Cuts All of Its Interest Rates, Including the Paper Currency Interest Rate, Negative Interest Rates are a Much Fiercer Animal"

Putting their model in the context of my post "The Supply and Demand for Paper Currency When Interest Rates Are Negative," they are treating the case of a Rate of Effective Return on Cash (ROERC) curve that is flat after a certain point. I argue in my post that is not the only plausible case. There are several other ways in which their model simplifies away from issues I have stressed on my blog:

1. Gauti, Ragnar and Ella deemphasize transmission mechanisms that do not involve banks, which I argue in three key posts are quite important:

However, even though there are transmission mechanisms that go around banks, causing problems for the banking system could easily be seen as an unacceptable side effect. I make this point in "What is the Effective Lower Bound on Interest Rates Made Of?"

2. In a way Gauti, Ragnar and Ella are very clear about, their model leaves out the subsidies that central banks pursuing negative interest rates can provide to private banks. Here is a key passage from pages 36 and 37:

Our model exercise focuses exclusively on the impact of negative policy rates39. Other monetary policy measures which occurred over the same time period are not taken into account. This is perhaps especially important to note in the case of the ECB, which implemented its targeted longer-term refinancing operations (TLTROs) simultaneously with lowering the policy rate below zero. Under the TLTRO program, banks can borrow from the ECB at attractive conditions. Both the loan amount and the interest rate are tied to the banks’ loan provision to households and firms. The borrowing rate can potentially be as low as the interest rate on the deposit facility, which is currently -0.40 percent40. Such a subsidy to bank lending is likely to affect both bank interest rates and bank profits, and could potentially explain why lending rates in the Euro Area have fallen more than in other places once the policy rate turned negative.

I have emphasized the importance of central bank subsidies to private banks in several posts:

3. In Gauti, Ragnar and Ella's model, if private banks tried to have negative rates on checking or savings accounts, all of their customers would turn to paper currency storage. But that is not the only possible interpretation of why they did not lower their checking and savings account rates below zero in negative interest rate companies. Thinking that even 5% of their customers would jump ship to another bank if they went first to negative checking and saving account rates would be enough to make these checking and saving account rates quite sticky at zero. But if the central bank took its target rate and interest on reserves into deeper negative territory, banks might lower their checking and saving account rates despite this fear. And if other banks followed suit, they might not lose as many customers as they feared.

In other words, isn't the first fear the fear of customers jumping to another bank if checking and saving account rates are reduced below zero, not paper currency storage? This would generate a stickiness that could be overcome in the way paper currency storage with a linear effective return of -.01 % annually cannot be overcome (without changing paper currency policy).

4. In line with much of the literature modeling monetary policy, Gauti, Ragnar and Ella do not have investment in the model. This makes their facsimile of the Great Recession in the model deficient. For what I consider a better model of the Great Recession, see "On the Great Recession."

Conclusion. I look forward to more articles doing formal models on negative interest rate policy. I wrote about paper that Gauti, Ragnar and Ella mention in "Markus Brunnermeier and Yann Koby's "Reversal Interest Rate." Matthew Rognlie has also written a nice paper in this genre: “What lower bound? Monetary policy with negative interest rates." 

I anticipate writing something in this genre myself at some point in the future. Right now my priorities in writing academic papers on negative interest rate policy are writing a second policy-focused paper with Ruchir Agarwal and a paper with Peter Conti-Brown on the law relevant to negative interest rate policies in the US.