For Estratos, studies by both the World Bank and the government suggest that this classification system no longer aligns well with the distribution of income (Figure 1.15). Some 90% of Colombians are in strata 1, 2 and 3. Moreover, because any house in a given area can be classified according to the mean for that neighbourhood, inaccuracies are inherent as many households living in these poor average strata belong to the upper income quintiles.