Most local economists say we do not have a bubble in Australian house prices. A bit overvalued, yes. But not a bubble. So why is it that overseas economists - such as Nouriel Roubini, the professor at New York University who predicted the collapse of US house prices that led to the global financial crisis, and Yale professor Robert Shiller, joint winner of the Nobel prize for economics - beg to differ?

Another American economist, Harry S. Dent jnr, in his new book: The Demographic Cliff- he's promoting it in Australia next month - makes special mention of Australia. He believes that house prices are unsustainable. But while others warn of a bubble in Australian house prices, Dent also identifies a possible deflation trigger - a crash in the Chinese housing market.

Property markets can be unstable. All it takes is ...

While Sydney and Melbourne house prices are high at almost 10 times income levels, the ratio is 35 times in the major Chinese city of Shenzhen. Dent says the collapse of Chinese housing prices will be the biggest housing crash in history. It will cause commodity prices to rapidly fall and cause the fall of Australian house prices.

At a ''bare minimum'' [Sydney] home prices will fall 27 per cent and return to what they were in 2005, Dent says. Dent writes a widely followed financial newsletter and his 2009 book, The Great Depression Ahead, was a bestseller. He tends to analyse economic trends through demographics. And Australia's population is ageing more slowly than many other developed countries.