Adventures in Identification III: The Indiana Jones of Economics 

 fabulous three part series on further adventures in identification on the Freakonomics blogs  here ,  here , and  here . The story features Kennedy School Professor Robert Jensen in his five year long quest of achieving rigorous identification for Giffen effects. After finding correlational evidence for Giffen goods in survey data he and his co-author actually followed up by running an experiment in China and guess what, they do find evidence for Giffen behavior. Impressive empirics and a funny read, enjoy!