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What is success, anyhow?

Markus Goldstein's picture

As a fair number of impact evaluations I work on are programs designed by governments or NGOs, I often initially have to have a tricky discussion when it comes time to do the power calculations to design the impact evaluation.   The subject of this conversation is the anticipated effect size.   This is a key parameter – if it’s too optimistic you run the risk of an impact evaluation with no effect even when the program had worked to some (lesser) degree, if it’s too pessimistic, then you are wasting money and people’s time in your survey. 

Fundamentally unknowable? Can we learn whether our firm policies in Africa are working?

David McKenzie's picture

Millions of dollars are spent each year trying to improve the productivity of firms in Africa (and those in other developing countries), yet we have very little rigorous evidence as to what works. In a new working paper I look at whether it is even possible to learn whether such policies even work, and what can be done to make progress.

Small number of firms + Large heterogeneity = Not much power

Stuff you cannot randomize...

Berk Ozler's picture

I have been thinking about marriage recently. No, not about my own marital status, but marriage among school-age girls and its effects on future outcomes… While many arguments are made to curb teen marriages (and pregnancies), it is not clear whether these events themselves are the cause of poor future outcomes or they are simply correlated with other background characteristics that are prognostic of future outcomes. A brief survey of the literature indeed suggests that the evidence is mixed; especially when it comes to the effects of teen childbearing on future outcomes.

Dean Karlan’s new book: RCTs – this time it’s personal!

David McKenzie's picture

More than Good Intentions: How a new economics is helping to solve global poverty is a personalized helicopter tour of many recent randomized controlled trials (RCTs) in developing countries. It is written by Dean Karlan, who has been a researcher in many of these experiments, and Jacob Appel, who worked for Dean in implementing many of these experiments in Ghana.

On experimental evaluations of systems interventions

Jed Friedman's picture

A quick look at the burgeoning literature on policy evaluations will reveal a preponderance of evaluations of demand side schemes such as conditional cash transfers. There is an obvious reason for this beyond the promise that such interventions hold: the technology of treatment allows for large sample randomized evaluations, either at the household or community/village level. As long as financing is sufficient to sample an adequate number of study units, study power will not be a concern.