1. Compare summary measures of inequality for all available countries on the OECD website:

• Plot the data for the ratio measures by changing the variable selected in the drop-down menu 'Gini coefficient'. The three ratio measures we looked at previously are called 'Interdecile P90/P10', 'Interdecile P90/P50', and 'Interdecile P50/P10', respectively. (If you click the 'Compare variables' option, you can plot more than one variable (except the Gini coefficient) on the same chart.)
• For each measure, give an intuitive explanation of how it is measured and what it tells us about income inequality. (For example: What do the larger and smaller values of this measure mean? Which parts of the income distribution does this measure use?)
• Do countries that rank highly on the Gini coefficient also rank highly on the ratio measures, or do the rankings change depending on the measure used? Based on your answers, explain why it is important to look at more than one summary measure of a distribution.

Figure 5.4 OECD countries ranked according to their Gini coefficient (2015).

The Gini coefficient and the ratios we have used are common measures of inequality, but there are other ways to measure income inequality.