Experimental Conversations: New Book on Randomized Controlled Trials

If you are interested in the use of randomized controlled trials (RCTs) in economics–particularly in development economics–Timothy Ogden has a new book out titled Experimental Conversations: Perspectives on Randomized Trials in Development Economics.

I am preparing a longer review that should see the light of day in the near future, but in the meantime, the book features a series of conversations with prominent economists–from Abhijit Banerjee and Esther Duflo to Angust Deaton, and from Jonathan Morduch to David McKenzie–not only about the advantages and disadvantages of RCTs, but also about the past, present, and future of RCTs.

If you are not already familiar with his work, Timothy Ogden is the managing director of the Financial Access Initiative at NYU, and he is the editor in chief of Philanthropy Action.

‘Metrics Monday: Testing for Mechanisms (and Possibly Ruling Out All Other Mechanisms) (Updated)

A few weeks ago, one of my doctoral advisees wrote to me asking me how she could test for a specific mechanism behind the causal effect she is trying to estimate in her job-market paper.

Letting $y$ be her outcome of interest, $D$ her treatment of interest, $x$ be a vector of control variables, and $\epsilon$ be an error term with mean zero, my student was estimating

(1) $y=\alpha_{0}+\beta_{0}{x}+\gamma_{0}{D}+\epsilon$,

in which she was interested in $\gamma$, or the causal impact of $D$ on $y$.

But more importantly for the purposes of this post, she was also interested in whether $M$ is a mechanism through which $D$ causes $y$. I suggested the usual thing I often see done, which is to estimate

(1′) $y=\alpha_{1}+\beta_{1}{x}+\phi_{1}{M}+\gamma_{1}{D}+\nu$,

in which case if $\gamma$ dropped out of significance and $\phi$ was significant (and had the “right”) sign, then she could say that $M$ was a mechanism through which $D$ cause $y$. I also suggested maybe conducting a Davidson-MacKinnon J-test for non-nested hypotheses to assess the robustness of her mechanism finding. Continue reading

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Agricultural Economists on the Cusp

Come gather ’round people
Wherever you roam
Around you have grown
And accept it that soon
You’ll be drenched to the bone
If your time to you is worth savin’
Then you better start swimmin’ or you’ll sink like a stone
For the times they are a-changin’

— Bob Dylan, “The Times They Are A-Changin’.”

On November 8, bucking the vast majority of polls, pundits, and prediction markets, Americans have elected Donald Trump as their president and have given him a majority of seats in both the Senate and the House of Representatives.

Whatever opinion I might have of the result of the election is immaterial, first because I am not a US citizen, and so I cannot vote in this country; and second, because I am not sure what the world needs at this point is more opinion.*

One thing I do have a cogent opinion on, however, is about the serious examination of conscience agricultural and applied economists need to do–especially left-leaning agricultural and applied economists.

First off, by “agricultural and applied economists,” I mean those of us who have any mix of research, teaching, and extension appointments in (what used to be known as) agricultural economics departments at land-grant universities. I know “applied economics” encompasses more than the category just delineated, but for the purposes of this discussion, I am choosing to go with the label the Agricultural and Applied Economics Association–my professional association–uses to designate people like my colleagues and me. Continue reading