Short answers, pulled from the story.
Italian statistician Corrado Gini introduced the concept in 1912 through his paper Variabilità e mutabilità. He built upon earlier research by American economist Max Lorenz to create this measure of inequality.
The value ranges strictly from 0 for total equality to 1 for absolute inequality if no negative incomes exist. The calculation equals area A divided by the total area of areas A and B combined on a Lorenz curve.
South Africa held the world's highest individual country score at 67.8 during that period. This figure represents the maximum inequality measured among all nations discussed in the script.
Global indices dropped from 0.80 in 1988 to 0.65 by 2013 due to rapid growth in emerging economies. Data estimates place global scores between 0.61 and 0.68 for the year 2005 before these trends reversed.
Bangladesh and the Netherlands both reported 0.31 in 2010 despite vastly different per capita incomes. One had $1,693 while the other possessed $42,183. These figures demonstrate how the coefficient measures relative wealth rather than absolute poverty levels.