Friday, September 01, 2017

Voter Irrationality and Systematic Bias: Applications in Food and Biotechnology

In the Myth of the Rational Voter: Why Democracies Choose Bad Policies, Bryan Kaplan discusses issues related to the median voter theorem and systematic biases by voters.

One interesting concept he discusses is the miracle of aggregation. According to the miracle of aggregation democracies can make decisions as if all were well informed. If we assume that less informed voters make random mistakes,  errors will cancel and the votes that matter will be the informed ones. The well informed median voter determines the outcome.

This all breaks down if the most informed voters make systematic mistakes. In that case the median preference becomes biased away from the optimal policy. But why would well informed voters make systematic mistakes?

Sometimes our values and views are part of who we are. Believing certain things gives people higher levels of utility. They let preferences drive beliefs over evidence. To entertain information or evidence to the contrary would upset preferences and lower utility. To quote Caplan:

"letting emotions or ideology corrupt thinking is an easy way to satisfy such preferences"

He also quotes Lebon:

"the masses have never thirsted after the truth, they turn aside from evidence that is not to their taste...whoever can supply them with illusions is easily their master; whoever attempts to destroy their illusions is always their victim"

This idea of preferences driving beliefs explains a lot. For instance, the election of demagogues. There are clear benefits to be reaped in customizing political platforms and media content that feeds into the preferences of these different segments of the population. The media capitalizes on that at the expense of actually informing the electorate. So do politicians and pundits.

This also may explain the explosion of growth in organic, natural, hormone free and other niche food markets.  Or the popular support for GMO labeling initiatives despite the science behind both safety and environmental benefits of biotechnology.

All of these are cases where acceptance of scientific evidence should potentially change opinions and behavior as it relates to food and agriculture. However to change those opinions and choices would be to drastically upset the preferences of a number of consumers. This makes it hard for those in agriculture and science communication trying to help the public navigate the complex world of modern agriculture. It also makes it hard for companies, wanting to do the right thing, to make a stand for science (i.e. by not going down the non-GMO/hormone/gluten free negative labeling route).

For instance, what if a t-shirt manufacturer wanted to promote the use of Bt cotton in their products on the basis of a reduction in use of toxic pesticides and improved insect biodiversity? Or what if a food company wanted to promote their dairy products for having a lower carbon footprint due to rBST? Taking this position would likely upset the illusions and preferences held dearly by many consumers. Noone wants to become 'their victim' to borrow from Lebon. Just ask Monsanto or BPI, the company behind finely textured beef. (however ABC eventually paid a price for feeding the masses the pink slime 'illusion'). In response, we don't see these kinds of promotions, and to the contrary we actually see companies removing these technologies from their product lines (and advertising the fact!).

Due to systematic bias in relation to food and technology, the median of voters' preference distribution will be biased toward more restrictive regulations than is scientifically appropriate. This will influence the types of products we see on the shelves and the potential for healthier and more environmentally sustainable solutions to challenging worldwide problems.


The Myth of the Rational Voter: Why Democracies Choose Bad Policies, Bryan Kaplan

The Crowd: A Study of the Popular Mind.  Gustave Le Bon.

A Meta-Analysis of Effects of Bt Cotton and Maize on Nontarget Invertebrates.Michelle Marvier, Chanel McCreedy, James Regetz, Peter Kareiva Science 8 June 2007: Vol. 316. no. 5830, pp. 1475 – 1477

Areawide Suppression of European Corn Borer with Bt Maize Reaps Savings to Non-Bt Maize Growers. Science 8 October 2010:Vol. 330. no. 6001, pp. 222 - 225 DOI: 10.1126/science.1190242W. D. Hutchison,1,* E. C. Burkness,1 P. D. Mitchell,2 R. D. Moon,1 T. W. Leslie,3 S. J. Fleischer,4 M. Abrahamson,5 K. L. Hamilton,6 K. L. Steffey,7, M. E. Gray,7 R. L. Hellmich,8 L. V. Kaster,9 T. E. Hunt,10 R. J. Wright,11 K. Pecinovsky,12 T. L. Rabaey,13 B. R. Flood,14 E. S. Raun15

The environmental impact of recombinant bovine somatotropin (rbST) use in dairy production Judith L. Capper,* Euridice Castañeda-Gutiérrez,*† Roger A. Cady,‡ and Dale E. Bauman* Proc Natl Acad Sci U S A. 2008 July 15; 105(28): 9668–9673

The environmental impact of dairy production: 1944 compared with 2007. Journal of Animal Science,Capper, J. L., Cady, R. A., Bauman, D. E. 2009; 87 (6): 2160 DOI: 10.2527/jas.2009-1781

Environmental impacts of genetically modified (GM) crop use 1996–2015: Impacts on pesticide use and carbon emissions
Graham Brookes & Peter Barfoot
GM Crops & Food Vol. 8 , Iss. 2,2017

Batista R, Saibo N, Lourenço T, Oliveira MM. Microarray analyses reveal that
plant mutagenesis may induce more transcriptomic changes than transgene
insertion. Proc Natl Acad Sci U S A. 2008 Mar 4;105(9):3640-5. doi:
10.1073/pnas.0707881105. PubMed PMID: 18303117; PubMed Central PMCID: PMC2265136

Baudo MM, Lyons R, Powers S, Pastori GM, Edwards KJ, Holdsworth MJ, Shewry PR. (2006). Transgenesis has less impact on the transcriptome of wheat grain than conventional breeding. Plant Biotechnol J. 2006 Jul;4(4):369-80

Sunday, August 27, 2017

Single Peaked Preferences and the Median Voter Theorem

In the last entry on voting paradoxes, I mentioned that things are different if preferences are single peaked.

Let’s look at another scenario. Again, consider a set of policies A,B,C following a sequence from  (A) less to more extreme (C) - maybe tax rates or some level of spending- with (B) being the intermediate policy. Suppose voters rank policies in order of preference/utility as follows:

Voter X:  ABC
Voter Y : CBA
Voter Z : BCA

In this case, no matter what order is undertaken, B always ends up being the law that is enacted. These preferences are single peaked. Each individual has a most preferred choice along the A to C spectrum. If you move away from that choice (in the A-B-C spectrum) they prefer the other choices less.  In the previous example, voter Y did not have single peaked preferences and that is what caused the cycling or order dependent outcomes. With single peaked preferences there is a new problem. With single peaked preferences, the median point of the preference distribution will elicit the most votes. Only those laws or candidates with a centrist twist will get the majority of the votes. Only those voters with centrist views will be happy, and it makes it very difficult for candidates to be elected if they want to bring about major reforms. This phenomenon is referred to as the ‘median voter theorem.’

Both voter cycling (when preferences are not single peaked) and the median voter theorem can have negative implications for majority rule policy adoption. Voters are either governed by irrational ever changing majorities, or they are subjugated by entrenched majorities whose views are maintained by the status quo of median preferences.


Lemieux, Pierre, The Public Choice Revolution. Regulation, Vol. 27, No. 3, pp. 22-29, Fall 2004. Available at SSRN:

Majority Rule and Vote Cycling with Non-Single Peaked Preferences

Is majority rule the best way to represent voters preferences for a given set of policies?

Let’s look at a particular voting scenario to illustrate this. Consider a set of policies A,B,C following a sequence from  (A) less to more extreme (C) - maybe tax rates or some level of spending- with (B) being the intermediate policy. Suppose voters have the following preferences:

VOTER X: A >B >C  'single peaked '


VOTER Z: B>C >A  'single peaked'

Both voters X and Z have single peaked preferences. As we move away from their optimal choice the strength of their preferences or utility decreases. However, voter Y does not exhibit single peaked preferences. They prefer the extreme policy C most, but their next preferred policy is in the direction of the other extreme A. They prefer the intermediate policy B least.

If the voters were voting on these issues, voter X would prefer law A over law B and law B over law C. In shorthand – A >B >C. To summarize all of the choices of the voters we see that 2/3 of the voters have preference A >B, 2/3 of the voters have preference B > C, but when voting A vs. C, 2/3 have preference C >A.

See if you follow the application of this. If we vote on policies in a pairwise fashion and have two elections and the first is made between policy B and C, then B will win (2/3 of the voters have preference B > C). If this is followed by a second election A vs. B (Because C was eliminated in the first election) then A will be the law that ultimately passes by majority rule.

Now if the order is changed, in which the first election is between A and B, A will win (because 2/3 of the voters rank A > B). Then in the second election when A goes against C, C will be the law that passes by majority rule (again because 2/3 of the voters have preference C >A).

So when voting on these policies, the process becomes arbitrary. The outcome depends on the order of the vote, so a cycling of choices ensues. According to public choice economist Gordon Tullock, any outcome can be obtained in majority voting by at least one voting method. This indicates that majorities can be irrational and dangerous unless preferences are all single peaked. 


Lemieux, Pierre, The Public Choice Revolution. Regulation, Vol. 27, No. 3, pp. 22-29, Fall 2004. Available at SSRN:

Thursday, August 24, 2017

Risk, Uncertainty, Speculation and Granger Causality

What is the difference between 'risk' and 'uncertainty'?

"Uncertainty refers to outcomes that we cannot foresee, or whose probabilities that we cannot estimate. In other words, uncertainty is a way of characterizing what we don't know about the distribution of the random variables themselves...Risk can be quantified, priced,and traded. It can even be hedged with large pools of assets." - Froeb et al 2014.Managerial Economics: A problem solving approach. 3rd edition.

This distinction was first made by economist Frank Knight.

Insurance of all kinds and commodity futures markets are examples of financial products based on quantifiable risks. Those involved in these markets, often speculators, have an important role to play. Speculators and futures and options markets make it possible to allocate resources across time, essentially from periods of abundance to periods of scarcity smoothing consumption and alleviating risks.

This is described well in The Economic Way of Thinking:

"Speculators coordinate market exchanges through time...that both inform people and provide them with the opportunity to allocate their risks...Speculators accept the risk at a mutually agreed upon price that hedgers seek to avoid."

Elaine Kub, author of Mastering the Grain Markets puts it beautifully in her book:

"All life on earth depends on agriculture, how well we distribute agriculture's products-how well we trade grain-determines how Earth's population gains access to its most fundamental needs."

However, speculators and funds involved in commodities trading often come under heavy scrutiny perhaps without understanding the important role they play in actually increasing food security as Nevil Speer explains below:

“Reining in speculators seems politically expedient.  But we live in complex times.  Throwing darts becomes perilous when policy makers begin to advocate (and worse yet, actually believe) that speculators should be removed  from ag / food markets.   Such a move would dismantle futures markets.  Imagine what the world might look like a without market liquidity, price discovery and risk mitigation; not to mention the inability to establish pricing plans, attract new capital investment and stimulate innovation across the food business.   The absence of those influences, facilitated by futures markets, would ultimately lead to less food production, availability and security – NOT the other way around.  Taking speculators out of the mix would be devastating.”  Dr. Nevil Speer, No Speculators? No thanks!, Drovers Cattle Network Agsight, March 2011

So what impact have speculators had on markets? One way is to look at the impact of index funds on commodity prices and volatility. Economist Scott Irwin at the University of Illinois has looked at this in depth. Below are three examples of studies (although not a complete review of the literature) looking at these impacts based on granger causality tests and other methods:

The Impact of Index Funds in
Commodity Futures Markets:
A Systems Approach
The Journal of Alternative Investments
Summer 2011, Vol. 14, No. 1: pp. 40-49

"The system of Granger-style causality tests fails to reject the null hypothesis that that trader positions do not lead market returns. Hence, there is no evidence of a linkage between index trader positions in commodity futures markets and price levels."

Irwin, S. H. and D. R. Sanders (2010), “The Impact of Index and Swap Funds on Commodity Futures Markets: Preliminary Results”, OECD Food, Agriculture and Fisheries Working Papers, No. 27, OECD Publishing. doi: 10.1787/5kmd40wl1t5f-en

“There is no statistically significant relationship indicating that changes in index and swap fund positions have increased market this time, the weight of evidence clearly suggests that increased index fund activity in 2006-08 did not cause a bubble in commodity futures prices.”

Index Trading and Agricultural Commodity Prices:
A Panel Granger Causality Analysis
Gunther Capelle-Blancard and Dramane Coulibaly
CEPII, WP No 2011 – 28
No 2011 – 28

"Our results show that, in agricultural futures markets, there is no evidence of a causality relationship from index funds to futures prices. This result holds for the period 2006-2010, but also for the sub-periods 2006-2008 and 2008-2010. These findings imply that index-based trading has not been an important driver in the substantial increase in commodities prices. Changes in commodity prices may instead reflect fundamental supply and demand factors."


Explained: Knightian uncertainty
The economic crisis has revived an old philosophical idea about risk and uncertainty. But what is it, exactly?
Peter Dizikes, MIT News Office
June 2, 2010

Foeb, Mcann, Ward, and Shor. Managerial Economics: A problem solving approach. 3rd edition. 2008.

The Economic Way of Thinking. Heyne, Boettke, and Prychitko. 10th Edition. 2002.

Mastering the Grain Markets: How profits are really made. Elaine Kub.

See also: 

Fat Tails, Kurtosis, and Risk

Fat Tails, the Precautionary Principle and GMOs

Friday, July 07, 2017

Stawman Arguments Against Statements Related to GMO Safety

Previously I discussed how the World Health Organization, the American Medical Association, and the National Academy of Sciences have all issued statements regarding the safety of foods derived from genetically engineered crops.

In addition I discussed how critics have questioned these statements. One set of assertions supports the invocation of the precautionary principle.

I have written before about issues related to using the precautionary principle with respect to genetically modified vs conventional food crops.

In this post I would like to specifically discuss the assertion that  "There are no epidemiological studies investigating potential effects of GM food consumption on human health."

To those unfamiliar with modern crop science and genetics, that could sound like a very condemning statement. But that begs the question, have there been epidemiological studies investigating the potential effects of conventionally and mutagenically improved crops on human health?

Its also a true statement that there are no epidemiological studies investigating the relative safety of using the stairs vs. elevators vs. escalators vs. leaping out the top floor window with regard to human health. (although I am sure actuaries have assessed property/casualty probabilities associated with similar kinds of risks related to building design, we don't have people losing sleep over lack of publication in this area)

These last examples might seem extreme and unrelated, but they illustrate the point that for some things, conducting an expensive (and difficult) epidemiological study to assess impacts on human health makes little practical sense. 

What reasoning would make us think this is necessary for genetically modified foods? If we were discussing inclusion of traits known to impact metabolism or hormone levels or some other biological function this might make sense. But the types of crops approved for human consumption don't have traits known to behave this way. Some critics might assert that it is the unknown consequences (changes in DNA, changes in proteins, or metabolism) that we should be worried about. 

However, scientists know that these kinds of genetic disruptions are not any more proliferate with genetically engineered crops than those related to traditional and mutagenic crop improvement that have been consumed and accepted by consumers without question for hundreds (thousands) of years or more in some cases and decades in others. They are substantially equivalent in this regard.

It turns out that the statement about the absence of epidemiological studies is really irrelevant when it comes to assessing the risks associated with genetically engineered food consumption. Arguments using epidemiological studies to form a psychological baseline or frame of reference are akin to strawman statements that could raise unnecessary doubts and fears about a technology that actually exhibits characteristics beneficial to human health and the environment.


No scientific consensus on GMO safety. Environmental Sciences Europe. 2015 27:4

Batista R, Saibo N, Lourenço T, Oliveira MM. Microarray analyses reveal that
plant mutagenesis may induce more transcriptomic changes than transgene
insertion. Proc Natl Acad Sci U S A. 2008 Mar 4;105(9):3640-5. doi:
10.1073/pnas.0707881105. PubMed PMID: 18303117; PubMed Central PMCID: PMC2265136

Baudo MM, Lyons R, Powers S, Pastori GM, Edwards KJ, Holdsworth MJ, Shewry PR. (2006). Transgenesis has less impact on the transcriptome of wheat grain than conventional breeding. Plant Biotechnol J. 2006 Jul;4(4):369-80
First citation:

Monday, July 03, 2017

Defining Consensus Regarding the Safety of Genetically Modified Foods

The World Health Organization, the American Medical Association, and the National Academy of Sciences have all issued statements regarding the safety of foods derived from genetically engineered crops. However, in a recent letter critical of the documentary film Food Evolution, the following paper is cited:

No scientific consensus on GMO safety. Environmental Sciences Europe. 2015 27:4

This was the first time I had seen this paper so I spent some time going through it to see what kinds of arguments were being made. Below are a few excerpts and some discussion.

"the scarcity and contradictory nature of the scientific evidence published to date prevents conclusive claims of safety, or of lack of safety, of GMOs. Claims of consensus on the safety of GMOs are not supported by an objective analysis of the refereed literature."
"The health, environment, and agriculture authorities of most nations recognize publicly that no blanket statement about the safety of all GMOs is possible and that they must be assessed on a 'case-by-case' basis."

"There are no epidemiological studies investigating potential effects of GM food consumption on human health"

"an expert panel of the Royal Society of Canada issued a report that was highly critical of the regulatory system for GM foods and crops in that country. The report declared that it is 'scientifically unjustifiable' to presume that GM foods are safe without rigorous scientific testing and that the 'default prediction' for every GM food should be that the introduction of a new gene will cause 'unanticipated changes' in the expression of other genes, the pattern of proteins produced, and/or metabolic activities."

"We support the application of the Precautionary Principle with regard to the release and transboundary movement of GM crops and foods."

 I have not had a chance to check every single reference and citation made. However the general framework sketched out in the paper I am getting is this:

  • there is no absolute or conclusive evidence that genetically engineered foods are safe or unsafe
  • the risks are associated with unintended effects related to gene insertions (i.e. genetic disruptions)
  •  invocation of the precautionary principle is used to obviate the statements often cited by the World Health Organization, the American Medical Association, and the National Academy of Sciences

This leads me to ask, can we make a blanket statement about the safety of all conventionally modified or organic foods that utilize plant breeding and mutagenesis? Have there been epidemiological studies investigating the effects of these methods on human health?

Suddenly this thinking brings up a question I have addressed before: why would we invoke the precautionary principle in the case of  food from genetically engineered crops and not for conventionally and mutagenically improved crops? 

From the literature:

“We found that the improvement of a plant variety through the acquisition of a new desired trait, using either mutagenesis or transgenesis, may cause stress and thus lead to an altered expression of untargeted genes. In all of the cases studied, the observed alteration was more extensive in mutagenized than in transgenic plants” - (Batista, et al; 2008)

With greater disruptions, critics might favor increased regulatory scrutiny. However, we do not have a framework in place for mutagenically improved crop varieties that have been safely used for decades and approved by the organic food industry and accepted by consumers, nor do we have anything like this for conventionally bred crops. If an argument for the precautionary principle holds for genetically engineered crops on this basis, then it should also hold for all types of crop improvement.

Therefore it seems tenuous to make a scientific risk based justification for special treatment of genetically engineered crops without further evidence. When many refer to a consensus on the safety of genetically engineered foods, this is what I have in mind.

Policies related to genetically engineered foods leveraging the precautionary principle could lead to increased risk of doing more harm than good to human health and the environment if policies prevent or delay adoption of traits that could decrease use of toxic pesticides, or reduce carbon emissions and improve soil conservation as some biotech traits have been shown to do in the literature.

See also:

Fat Tails, The Precautionary Principle, and GMOs
Comments on Rules for Gene Editing Technology
Organic Activists Realize Hypocrisy in Opposition to Gene Editing Technology


Batista R, Saibo N, Lourenço T, Oliveira MM. Microarray analyses reveal that
plant mutagenesis may induce more transcriptomic changes than transgene
insertion. Proc Natl Acad Sci U S A. 2008 Mar 4;105(9):3640-5. doi:
10.1073/pnas.0707881105. PubMed PMID: 18303117; PubMed Central PMCID: PMC2265136

Baudo MM, Lyons R, Powers S, Pastori GM, Edwards KJ, Holdsworth MJ, Shewry PR. (2006). Transgenesis has less impact on the transcriptome of wheat grain than conventional breeding. Plant Biotechnol J. 2006 Jul;4(4):369-80

Sunday, July 02, 2017

Are Soda Taxes Effective

Over at RealClearAgriculture I have been blogging about food subsidies and soda taxes.

Research from the American Journal of Clinical Nutrition finds no link to obesity and soft drink consumption.

"We showed no association between sugar-sweetened
beverage consumption, juice consumption, and adolescent weight
gain over a 5-y period. A direct association between diet beverages
and weight gain appeared to be explained by dieting practices.
Adolescents who consumed little or no white milk gained significantly
more weight than their peers who consumed white milk. Future
research that examines beverage habits and weight among adolescents
should address portion sizes, adolescent maturation, and dieting behaviors."

This corroborates previous findings from the journal Nutrition:

"Our analysis shows no evidence for an association between SSB consumption at age 5 or 7 y and fat mass at age 9 y in this cohort of British children"

A recent blog post (link) gets close to accurately reporting the issue of high fructose corn syrup- a sweetener chemically identical to table sugar found in soft drinks:

"Fructose and high-fructose corn syrup aren't the same. It appears that the writer, Lois Rogers, conflated the two and jumped to all kinds of incorrect conclusions. For example, that the research had anything at all to do with "the obesity epidemic." It didn't."

"The environmental site Grist tends to see everything through an ideological lens, and so is always on the hunt for evidence that high-fructose corn syrup is somehow more harmful than common sugar"

But then the article starts to get off track in stating:

"It is cheap (high fructose corn syrup) in large part because of farm subsidies. As a result, it is ubiquitous and is making a lot of people fat, diabetic, and prone to heart disease."

Research taking the claim of a connection between obesity and farm policy in a more direct fashion can be found here( from UC Davis).

"'The culprit here is not corn subsidies; rather,it is sugar policy that has restricted imports, driven up the U.S. price of sugar, and encouraged the replacement of sugar with alternative caloric sweeteners...Given that consumers generally show limited responses to retail food price changes, eliminating the corn subsidy would reduce corn-based food consumption by at most 0.2 percent.""

Similarly, this weak response of consumers to food prices undermines policies that advocate taxing soft drinks to reduce consumption and obesity. Research ( from the Mercatus Center at George Mason University) indicates that the taxes required to have any real affect on obesity would be in the 1200 percent range, and even if taxes eliminated ( in this case soda) consumption, the impact on obesity would be very small. The study concludes that "the sensitivity of individuals to changes in relative food prices is not sufficient to make “fat taxes” a viable tool to lower obesity."

These campaigns are nothing more than emotional appeals designed to solicit support for new taxes and regulations that ultimately undermine the agriculture industry and family farms.


Media Gets Stuck in High-Fructose Corn Syrup
Dan MItchell
Daily Bread, The Business of Food Blog
The Big Money by Slate

Am J Clin Nutr doi: 10.3945/ajcn.2009.27573
Adolescent beverage habits and changes in weight over time:
findings from Project EAT1–3
Michelle S Vanselow, Mark A Pereira, Dianne Neumark-Sztainer, and Susan K Raatz

Nutrition July-August 2007, Volume 23, Issues 7-8, Pages 557-563
"Is sugar-sweetened beverage consumption associated with increased fatness in children?"

Taxing Sins: Are Excise Taxes Efficient
The Mercatus Center
George Mason University

Farm Subsidies and Obesity in the United States
Julian M. Alston, Daniel A. Sumner, and Stephen A. Vosti
Agricultural and Resource Economics Update
University of California
V. 11 no. • Nov/Dec 007

Monday, June 19, 2017

Food Facts: Food Insecurity and Food Deserts

According to the USDA, "an estimated 12.7 percent of American households were food insecure at least some time during the year in 2015, meaning they lacked access to enough food for an active, healthy life for all household members."

Here are a few more notes:

1) 5.0 percent of U.S. households (6.3 million households) had very low food security
2) There were sizable differences by state
3)   ~59% used SNAP, WIC, or the national school lunch program in the previous month
4)  The median food-secure household spent 27 percent more for food than the typical food-insecure household

Prices Matter

In a 2013 Applied Economic Perspectives and Policy article, researchers found a significant impact of local food prices on food insecurity developing a novel index of local food prices:

“We find that the average effect of food prices on the probability of food insecurity is positive and significant: a one-standard deviation increase in food prices is associated with increases of 2.7, 2.6, and 3.1 percentage points in household, adult, and child food insecurity, respectively. These marginal effects amount to 5.0%, 5.1%, and 12.4% increases in the prevalence of food insecurity for SNAP households, adults, and children, respectively. These results suggest that indexing SNAP benefits to local food prices could improve the ability of the program to reduce food insecurity and economic hardship more generally in areas with high food prices.”

Food Insecurity, SNAP, and Health Outcomes

In 2012, researchers publishing in the Journal of the American Statistical Association found that SNAP can have positive mitigating effects on the health of children.

"Under stronger but plausible assumptions used to address the selection and classification error problems, we find that commonly cited relationships between SNAP and poor health outcomes provide a misleading picture about the true impacts of the program. Our tightest bounds identify favorable impacts of SNAP on child health."

Gundersen (2015) finds a relationship between food insecurity and health outcomes for children and seniors.

"after confounding risk factors were controlled for, studies found that food-insecure children are at least twice as likely to report being in fair or poor health and at least 1.4 times more likely to have asthma, compared to food-secure children; and food-insecure seniors have limitations in activities of daily living comparable to those of food-secure seniors fourteen years older. The Supplemental Nutrition Assistance Program (SNAP) substantially reduces the prevalence of food insecurity and thus is critical to reducing negative health outcomes"

What we can conclude from this research is that  prices matter - while policies that help reduce or subsidize the purchase price of food can help reduce food insecurity and provide positive outcomes, policies that increase prices could have the opposite effect.

What about food deserts?

Over at the UofI Policy Matters blog, Craig Gundersen and others discuss the relationship between food deserts and prices. They cite a few studies:

Availability And Prices Of Foods Across Stores And Neighborhoods: The Case Of New Haven, Connecticut. Health Aff September 2008 vol. 27 no. 5 1381-1388

The above was a case study looking at stores across lower vs higher income neighborhoods. They find lower quality and fewer options in the lower income stores.

Does Healthy Food Cost More in Poor Neighborhoods? An Analysis of Retail Food Cost and Spatial Competition. Patrick L. Hatzenbuehler, Jeffrey M. Gillespie, and Carol E. O’Neil. Agricultural and Resource Economics Review 41/1 (April 2012) 43–56 

The above was an interesting study that found that the impacts of spatial distribution of store locations impacted consumption, although there were no price effects.

 In their blog post, the authors discuss how they develop a local price index for food bundles and compare prices for areas that are and are not classified as food deserts.

"Our findings suggest that living in a food desert affects the overall food prices faced by households to a small extent when consumers can shop within their home census tracts and in contiguous census tracts. The difference in prices is largely driven by differences in available variety. As such, while higher food prices are associated with higher rates of food insecurity, the results of our work suggest that living in a food desert is unlikely to influence food insecurity to a great extent"

In their related paper, presented at the 2015 Agricultural and Applied Economics Association and Western Agricultural Economics Association annual meeting you can read more.


Alisha Coleman-Jensen, Matthew P. Rabbitt, Christian A. Gregory, and Anita Singh.
Household Food Security in the United States in 2015, ERR-215, U.S. Department of
Agriculture, Economic Research Service, September 2016.

Christian A. Gregory, Alisha Coleman-Jensen; Do High Food Prices Increase Food Insecurity in the United States?. Appl Econ Perspect Policy 2013; 35 (4): 679-707. doi: 10.1093/aepp/ppt024

Kreider, B., Pepper, J. V., Gundersen, C., & Jolliffe, D. (2012). Identifying the effects of SNAP (Food Stamps) on child health outcomes when participation is endogenous and misreported. Journal of the American Statistical Association, 107(499), 958-975. DOI: 10.1080/01621459.2012.682828

Gundersen C, Ziliak J. Food insecurity and health outcomes. Health Affairs 2015;34(11):1830-1839.

Sustainably Feeding the World: Organic Food and Vegetables vs Conventional Commodities

Can we feed the world sustainably using organic crop production methods? Several studies have indicated that there is a yield penalty for organic crops

The crop yield gap between organic and conventional agriculture. Agricultural Systems
Volume 108, April 2012, Pages 1-9

The above indicates ~ 20% yield penalties for organic vs conventional production

Comparing the yields of organic and conventional agriculture. Nature 485,229–232.(10 May 2012) doi:10.1038/nature11069 

The above finds a range of differences in yield between organic and conventional agriculture, from 5-35% depending on different crops, practices, and conditions.

Alexandra N. Kravchenko, Sieglinde S. Snapp, and G. Philip Robertson. Field-scale experiments reveal persistent yield gaps in low-input and organic cropping systems
PNAS 2017 114 (5) 926-931; published ahead of print January 17, 2017, doi:10.1073/pnas.1612311114 

The above indicates much of the previous research was based on research plots, and penalties for organic vs conventional yields could actually be worse when scaled up to field size production practices.

To what extent does organic farming rely on nutrient inflows from conventional farming?
Benjamin Nowak1,2, Thomas Nesme1,2, Christophe David3 and Sylvain Pellerin1,2
Published 5 December 2013  2013 IOP Publishing Ltd
Environmental Research Letters, Volume 8, Number 4 

The above research indicates there are significant inflows of N, P, K from conventional sources. For example, many organic production systems may rely on manure from animals raised or fed conventionally. If these positive exteranalities were excluded, the increased energy and land devoted to organic production would reduce its sustainability further.

 Often in addition to some calling for increased organic food production, you will hear additional criticisms of commodity or 'monocrop' agriculture. Themes include criticisms of agricultural policies favoring 'industrial' agriculture at the expense of healthy fruits and vegetables. However, these criticisms ignore the importance of calorie density and consumption at a global level. According to the FAO rice, corn, and wheat provide 60% of the world's energy intake. Costs of production and economies of scale favor large scale production of these staples over specialty crops like broccoli and tomatoes when it terms of providing affordable calorie dense food to a growing population.

Additional References:

Greenhouse gas mitigation by agricultural intensification Jennifer A. Burneya,Steven J. Davisc, and David B. Lobella.PNAS  June 29, 2010   vol. 107  no. 26  12052-12057