52 search results for "farmers' markets"

Back from spring break which, even though I am on leave this semester, I used to take a break from blogging and travel to (i) Peru, to assess the feasibility of field experiments I am planning on conducting there and (ii) Ithaca, NY, to present my work on farmers markets and food-borne illness at the Dyson School of Applied Economics and Management in the future Cornell College of Business.

For today’s installment of ‘Metrics Monday, suppose you have data that consists of repeated cross sections. To take an example from my own work, suppose you have 10 years worth of a nationally representative household survey, but the data are not longitudinal. That is, for each year, whoever was in charge of collecting the data collected them on a brand new sample of households.

Obviously, because the data are not longitudinal, the usual panel data tricks (e.g., household fixed effects) are not available. So what can you do if you want to get closer to credible identification?

It is not uncommon for the New York Times to discuss food policy. It is much less common for the newspaper of record to discuss Food Policy, the Elsevier journal I have the honor of co-editing, along with my Mario Mazzocchi. Yet the Gray Lady did just that last week when it discussed food labeling:

The Senate could soon join the House to try to make it harder for consumers to know what is in their food by prohibiting state governments from requiring the labeling of genetically modified foods. This is a bad idea that lawmakers and the Obama administration should oppose. …

There is no harm in providing consumers more information about their food. A study published in the journal Food Policy in 2014 found that labels about genetic modification did not influence what people thought about those foods. Some companies are deciding on their own to increase the information they provide to consumers without fear of losing sales.

Rob writes:

I am not an econometrician–I spend my time playing with CGE models–but have to know something about econometrics. Recently I have been reviewing draft papers on a project using detailed tax data in my country–firm-level, matched with individual returns of employees, valued-added tax, import duties, etc.–for the period 2009-2014. A massive and rather unusual database.

It is all good work, but I have two concerns. (Note: I will get to Rob’s second concern at next week’s installment of ‘Metrics Mondays. — MFB.) One is about big data. Many of the researchers report t-statistics and other statistics as if this does not matter. In fact some say they are dealing with the population of firms, in which case my sense is that standard errors say nothing about statistical fit, but maybe about economic significance of relations between means. Even if it is a sample, as n/N becomes closer to 1, sample statistics become problematic.

That is a very interesting question. Let me just rephrase it a bit more broadly to this: What do you do when you are dealing with the population itself instead of dealing with a sample that is representative of a population?