Skip to content

Category: Food

Published January 30, 2012

Who Wins and Who Loses During Food Crises?

In a very good article in the latest issue of Science, Jo Swinnen and one of his coauthors explain that, as with many other changes in economic circumstances, rising food prices are a boon to some people and a bane to others. Here is the summary:

Spikes in food prices have pushed food security to the top of the global policy agenda. Price increases have mixed effects on poverty and hunger: They increase the cost of food for consumers but increase incomes of farmers, who represent the bulk of the world’s poor. Net effects will differ depending on whether poor households or countries buy or import, or sell or export food (infrastructure, institutions, and market imperfections will play roles, as well). Policies to influence prices imply winners and losers, not just between rich and poor, but also among the poor. These nuances are too often absent in public debate, to the detriment of policy-making. Moreover, the arguments put forward today, that high food prices generally hurt the poor, are in contrast with those put forward a few years ago, that low food prices were hurting the poor.

Put simply, when food prices rise, food producers benefit and food consumers lose out. But while the media used to causally link low food prices to poverty and hunger, it was high food prices instead that were blamed for poverty and hunger during the food crises of 2008 and of 2010-2011.

Continue readingWho Wins and Who Loses During Food Crises?
Published January 23, 2012

Does Participation in Agricultural Value Chains Make Smallholders Better Off?

Yes, it does.

At least, that is my answer to the question in a new article of mine titled “As You Sow, So Shall You Reap: The Welfare Impacts of Contract Farming,” which is forthcoming in World Development.

More specifically, I try to estimate the causal impacts of participation in contract farming — the economic institution in which a processing firm contracts its production of agricultural commodities out to grower households, or the first link in an agricultural value chain — on the welfare of the smallholders.

The major difficulty with studying such problems is that households are not randomly assigned to the treatment (i.e., participants in contract farming) and control (i.e., nonparticipants in contract farming) groups.

The smallholders who choose to participate in agricultural value chains do so following systematic patterns. The problem is that the researcher has no idea what those patterns are, as they often involve variables that are unobserved.

For example, it could be that more entrepreneurial smallholders are less likely to participate in agricultural value chains because they have better options. Or it could be that smallholders who are risk-averse are more likely to participate in agricultural value chains because contract farming partially insures them against income risk. But if it is difficult to measure risk aversion, it is even more difficult to measure entrepreneurial ability.

Continue readingDoes Participation in Agricultural Value Chains Make Smallholders Better Off?
Published January 10, 2012

Taubes on the Weakness of Observational Studies, and a Methodological Rant

One caveat is observational studies, where you identify a large cohort of people – say 80,000 people like in the Nurse’s Health Study – and you ask them what they eat. You give them diet and food frequency questionnaires that are almost impossible to fill out and you follow them for 20 years. If you look and see who is healthier, you’ll find out that people who were mostly vegetarians tend to live longer and have less cancer and diabetes than people who get most of their fat and protein from animal products. The assumption by the researchers is that this is causal – that the only difference between mostly vegetarians and mostly meat-eaters is how many vegetables and how much meat they eat.

I’ve argued that this assumption is naïve almost beyond belief. In this case, vegetarians or mostly vegetarian people are more health conscious. That’s why they’ve chosen to eat like this. They’re better educated than the mostly meat-eaters, they’re in a higher socioeconomic bracket, they have better doctors, they have better medical advice, they engage in other health conscious activities like walking, they smoke less. There’s a whole slew of things that goes with vegetarianism and leaning towards a vegetarian diet. You can’t use these observational studies to imply cause and effect. To me, it’s one of the most extreme examples of bad science in the nutrition field.

That’s Gary Taubes in a FiveBooks interview over at The Browser. Taubes is better known for his book Good Calories, Bad Calories, in which he argues that a diet rich in carbohydrates is what makes us fat and, eventually, sick, and in which he argues in favor of an alternative diet rich in fats.

I really don’t know what kind of diet is best for weight loss, but I do want to stress Taubes’ point about the weakness of observational studies, even longitudinal ones. It is not uncommon for social science researchers to say “Well, we’ve been following these people over time, so we can use fixed effects to control for unobserved heterogeneity.” That is, they control for what remains constant for each unit of observation over time, which is made possible because they have more than one observation for each unit of observation. I have certainly been guilty of that.

Continue readingTaubes on the Weakness of Observational Studies, and a Methodological Rant