Intuition for tight bounds under noncompliance
From Erich Battistin, University College, London:
I'm a Ph.D. student in statistics at the Dept. of Economics of UCL, London; in the last few months I went through your papers (and your book) about causality – in particular, I paid more attention to your result on the improvement of Manski's bounds on treatment effects when we have imperfect compliance. This result is certainly powerful but – leaving out technicalities – I don't really understand which information your approach exploits that the one by Manski does not. What is the intuition behind? I didn't find this point explained in any paper I read (but obviously to deal with an 'econometric-based' audience as the one here at UCL you need to make this point clear).