What factors influence income inequality?

Source: Dale O. Cloninger, The Conversation, July 21, 2016

…Nevertheless, most would agree that reducing the inequality gap is a worthy goal. Understanding what is causing the growing gap between rich and poor is key to figuring out how to reduce it.

Is it driven by natural causes such as age that can’t be easily effected by policy? Or is inequality rooted in more malleable factors like education or tax policy?

A statistical analysis of 53 countries that emerged from a graduate student’s research project provides some clues. And the analysis begins with what social scientists call the Gini coefficient.