"Different sorts of decisions need different sorts of evidence, just as [Jane] Jacobs said different sorts of businesses need different sorts of buildings. In particular, new ideas need cheap tests, just as new businesses need cheap rent. As an idea becomes more plausible, it makes sense to test it in more expensive ways."That is from a nice post by Seth Roberts. It is highly germane to many endeavors in life, including international aid. Good progress has been made recently on the gold standard of (well-designed) randomized controlled trials (RCTs) testing aid project design.
But RCTs can be expensive and cannot be done in all circumstances. So we need a menu of approaches to determine whether different types of ideas at various stages idea are promising.
I recently had an interesting conversation along these lines with one of the creators of an innovation fund at a major aid agency. I hope soon to be able to post an interview online with him here.