This happiness index (pdf) is based not on subjective questions, but on "revealed preferences," using migration as a standard; that is, what people do, not what they say. 
Hiki Kielelezo cha Furaha (pdf) hakitokani na maswali huru yaliyoulizwa, bali kimetokana na "utashi uliogunduliwa," kwa kutumia uhamaji kama kigezo; yaani, kile watu wanachokifanya, na sicho kile wanachokisema.