I delivered a talk at 3ie’s Delhi Seminar Series on a recently published PLoS ONE paper) and follow-up research.

Suppose you toss a coin and it comes up heads. Do you conclude that it is a double-headed coin? No, you don’t. Suppose it comes up heads twice, and then a third time. Do you now conclude the coin is double-headed? Again, no you don’t. There is a one in eight chance (12.5 per cent) that a coin will come up heads three times in a row. So, though it is not that likely, it can and does happen.

We expect researchers to defend their assumptions when they write papers or present at seminars. Well, we expect them to defend most of their assumptions. However, the assumptions behind their sample size, determined by their power calculations, are rarely discussed. Sample sizes and power calculations matter. Power calculations determine sample size requirements, which match budget constraints with minimum sample size requirements.

At its annual colloquium being held in Hyderabad, India, the Cochrane Collaboration is focusing on evidence on the global burden of disease of mostly treatable illnesses that are concentrated among populations living in low- and middle-income countries (L&MICs).  We already have a lot of systematic review evidence about what works to prevent and treat them.  Yet they remain prevalent due to the lack of resources, implementation capacity and pop