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Power calculations: what software should I use?

Berk Ozler's picture

In my experimental work, I almost always do cluster-randomized field experiments (CRTs – T for trials), and therefore I always used the Optimal Design software (OD for short), which is freely available and fairly easy to use with menu based dialogue boxes, graphs, etc. However, preparing some materials for a course with a couple of colleagues, I came to realize that it has some strange basic limitations. That led me to invest some time into finding out about my alternatives in Stata. I thought I’d share a couple of things I learned here.

Weekly links June 26: hurting power, banning bottled water, the case against training, and more…

David McKenzie's picture

Do More Hours Equal More Learning? Probably, But It Isn't Cheap

David Evans's picture
In many countries around the world, universal primary school enrollment has been achieved. But quality remains an ongoing challenge. How do you get students to learn more? One solution that comes up often in Latin America and the Caribbean is to increase the length of the school day. From Mais Educação in Brazil to Jornada Escolar Completa in Chile, many governments are considering or are already rolling out additional hours to the school day.

Will more hours help?

Another reason to prefer Ancova: dealing with changes in measurement between baseline and follow-up

David McKenzie's picture
A few months ago, Berk blogged about my paper on the case for more T, and in particular, on the point that Ancova estimation can deliver a lot more power than difference-in-differences when outcomes are not strongly autocorrelated.

Randomizing Competition: allowing CCT recipients to get more goods for their money

David McKenzie's picture
The Dominican Republic’s Solidaridad conditional cash transfer program provides its monetary transfers to poor families in the form of a debit card that can only be used at a network of grocery stores affiliated with the program (it does this in part to ensure they spend the money on food). The typical monthly transfer is about $36, which is 17% of median monthly food expenditure.

Pitch Perfect? An Update on the SME Ideas Competition

David McKenzie's picture
One of the benefits of impact evaluation has been fostering more collaboration between researchers and operational staff implementing projects. However, at present this collaboration largely happens once the project itself has been decided upon. To try and get more researcher ideas influencing what projects get done in the first place, I partnered with the World Bank’s Innovation and Entrepreneurship unit to hold a competition for new ideas for SME projects, financed by DFID under part of a Strategic Research Program (SRP) program grant (I previously blogged about the launch).
As a pilot initiative, our key questions were:
  • Is there a supply of new ideas that researchers have that are not currently being tried? Will researchers take the time to put these ideas forward?
  • Is there a demand from operational teams and governments working on SME projects for new ideas in this space?
  • Can we form matches between this supply and demand?

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