Another 2008 paper by the same authors experimentally demonstrated the existence of Giffen goods among people at the household level by directly subsidizing purchases of rice and wheat flour for extremely poor families. It is easier to find Giffen effects where the number of goods available is limited, as in an experimental economy: DeGrandpre et al. (1993) provide such an experimental demonstration. In 1991, Battalio, Kagel, and Kogut published an article arguing that quinine water is a Giffen good for some lab rats. However, they were only able to show the existence of a Giffen good at an individual level and not the market level.