WHY DOES INEQUALITY MATTER?
Recent studies suggest that inequality isn't just bad for those at the bottom - it affects people all along the income scale.
One study by the OECD suggests rising inequality was responsible for wiping a third off New Zealand's economic growth in the past 30 years.
It estimated the rate of New Zealand's GDP growth was stunted by as much as 15.5 percentage points between 1990 and 2010 - more than any other OECD economy.
Max Rashbrooke , editor of Inequality: A New Zealand crisis, says a growing income gap causes people to "lose their sense of what life is like for people in the other half".
"They trust each other less, and they care about each other less and so they're less likely to extend a helping hand and feel like they've got something in common with everyone else," he says.
There'll always be a bit of inequality in any society, says Rashbrooke , "the question is at what point does it become really problematic"?
"One of the ways that you know it's a real problem is you no longer have any meaningful social mobility."
In 1986, the top 10 per cent took home 26.5 per cent of New Zealand's income. In 1999, it was 37.8 per cent and in 2004, it was 33.2 per cent.