Giffen Goods In Consumer Theory

There is a type of special merchandise in the word of numerous and complicated merchandise, when the price soar, peoples demand to it would not descend, but on the contrary increase and people called this merchandise Giffen goods.Although there is still an argumentation about whether Giffen goods exist, is an undisputable fact that the word "Giffen" appear in the economics teaching material.But why the issue of the existence of Giffen goods would keep on for long 150years in economics field? Because the condition of the existence of Giffen merchandise is extraordinarily rigorous, causing the Giffen case be also extremely rare. The Giffen merchandise is a kind of inferior and daily necessity, but the expenditure has to share a very big proportion of the consumers'income.So Giffen merchandise is only for those who can just earn their living and have a little bit more.It is difficult to find out such consumer community.Based on the assumption that when the price of merchandise is increasing, the index number of consumers" preference were constant,to find out the critical point of consumer income,and accordingly measure of the existent space of the Giffen merchandise.Put forward some comparatively better index numbers,according to which to judge whether a certain inferior merchandise is Giffen merchandise or not!A11 of this the main work of this paper.