Well , I strongly disagree with the whole a strong jaw is an important feature for a man bullshit . You don ' t need a sharp jaw to look good . I really think your jaw is fine And trust me , I get the frustration , I also don ' t have a very strong jawchin but thinking it ' s that bad is all in your head . <| sep |> Looks like it ' s a known issue they ' re working on resolving . <| sep |> As uCornCobbDouglas said , demonstrating causality is really hard for these kind of economic claims . Usually you want a good instrumental variable , but you need to give good evidence that your instrument isn ' t being or less uncorrelated with anything else in the system . Abnormal rainfall like drought events should be totally random , making them a good instrument for countrywide water availability , but theywon ' t give you any information on water infrastructure itself . Maybe you could look at the operations of water charities in very poor countries with similar GDP per capita say under $ 1000 , and use levels of spending per capita of those charities on local water projects as an instrument . I ' m not convinced that the activities of water charities aren ' t affected by hidden variables , but it might be something worthwhile to check out .