Women are twice as likely to be underpaid compared to men if they are not in a union. Indigenous Australians are three times as likely to be underpaid.

The finding, from research conducted by Andrew Leigh, a Labor frontbencher and former professor of economics, will be unveiled in a speech on Monday that will defend the role of trade unions and home ownership, both of which he says were strong under the long-serving Coalition prime minister Robert Menzies and are under attack by Malcolm Turnbull.

Labor's shadow assistant treasurer Andrew Leigh. Credit:Louise Kennerley

"At the end of World War Two, Australia was a nation where just 53 per cent of households owned their homes," he will tell the Per Capita Reform Agenda conference in Sydney. "In the major cities, the figure was 46 per cent. Most city-dwellers rented.

"Then in the post-war years, something remarkable happened: the Australian home ownership rate surged. By 1961 it was 70 per cent. In just over a decade the distribution of Australian housing wealth became significantly more equal.