Thus, the HOI is used to measure the degree of equality of opportunity on a scale that goes from 0 to 1, with 0 representing absolute inequality and 1 being equivalent to full equality of opportunity. This indicator serves as a yardstick for the distribution of social services within a country by income level, in other words, it measures the concentration of public social services by geographic area (urban/rural) and by income distribution. A comparison made using a sample of 16 Latin American countries yields a negative relationship between the two (see figure 8): countries with low HOI ratings, such as El Salvador, Guatemala and Honduras, have high murder rates, whereas countries with high HOI ratings, such as Argentina, Chile, Costa Rica and Uruguay, have low murder rates. The productivity gains associated with greater equality of opportunity drive up wages and thus reduce violence and poverty rates.