The researchers took into account both economic and non-economic factors of happiness, which overlap with what can be considered the determining factors of migration: absolute and relative income, demographic and social characteristics, social development, relationships with others and characteristics of the place where one lives, as well as variables like distance or a common border and language. 
Watafiti walizingatia sababu za kiuchumi na zile zisizo za uchumi zinazomfanya mtu kuwa na furaha, ambazo zinaingilia na na kile kinachoweza kuchukuliwa kuwa mambo yanayosababisha uhamaji: kipato kisichotosha, sura ya idadi ya watu wa mahali, maendeleo ya kijamii, mahusiano na watu wengine na sifa za mahali anakoishi mtu, pamoja na vibadilika (viriables) kama umbali au kupakana kwa nchi na lugha.