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Martin Ravallion's blog

Can we trust shoestring evaluations?

Submitted by Martin Ravallion on Wed, 2012-03-07 10:56

There is much demand from practitioners for “shoestring methods” of impact evaluation—sometimes called “quick and dirty methods.” These methods try to bypass some costly element in the typical impact evaluation. Probably the thing that practitioners would most like to avoid is the need for baseline data collected prior to the intervention. Imagine how much more we could learn about development impact if we did not need baseline data! Even with the expansion in impact evaluations over the last 10 years or so, I doubt if any form of contemporaneous baseline data are available for more than 10% of current development projects. (Less than 10% of the World Bank’s lending operations have impact evaluations, and I doubt if the Bank evaluates less than average.) Should we just give up on the 90%?

Do our development practitioners have an incentive to learn? And do they learn?

Submitted by Martin Ravallion on Sun, 2011-12-04 18:32

It is well recognized that the stock of knowledge among development practitioners matters to development impact. How then do the operational staff of the largest international development agency value and use its research for their work?

The Research Support team in the World Bank’s Development Economics Vice- Presidency recently surveyed 550 of the Bank’s senior operational staff. One question asked what value respondents attached to Bank research for their work, on a 10-point scale where 1=”not valuable at all” and 10=”extremely valuable.” Answers covered the whole range. Over half the sample gave an answer of 6 or more; two thirds gave an answer of 5 or more. Many operational staff appear to have a reasonably strong incentive to learn about Bank research, though it is stronger for some than for others.

Development impact calls for knowledgeable development practitioners

Submitted by Martin Ravallion on Thu, 2011-10-06 14:00

These days we talk a lot about how best to assess development impact through evaluative research. Sound data and methods are essential. Here there has been considerable progress over the last 20 years or so.

All that progress will come to nothing if it does not make those people actually doing development more knowledgeable about what they are doing.  This depends in part on whether the research that is done is useful and well disseminated. Here there has also been progress, though more work is needed.

Should you care about impact heterogeneity?

Submitted by Martin Ravallion on Sun, 2011-09-25 21:32

If you want to know the average impact of being assigned the option of some “treatment”— the so-called “intent-to-treat” parameter—then you will get a good (unbiased) estimate by comparing the mean outcome for an experimental group that is randomly assigned the treatment with that for another group randomly denied that option.