When does a housing bubble start?

Yesterday, former Minister for Finance Charlie McCreevy appeared before the Oireachtas banking enquiry. His refusal to answer whether or not he believed Ireland suffered a property bubble that burst in 2007 was not only great TV, it also brings up some important issues. For example, the Irish Independent reports:

The conflict arose when Mr Doherty asked the former minister if he believed there had been a property bubble in the previous 15 years before the financial crisis. Mr McCreevy insisted he would only answer for his time in office and there had been no property bubble during that time… [after legal advice] Mr McCreevy said from 2003 to 2007 house prices grew at an extraordinary rate. He supposed that was a bubble. But he said: “I don’t believe the policies I pursued helped to create that bubble.”

The clear implication is that Mr McCreevy believes that, if there was any housing bubble at all, its roots do not lie in decisions made in the period 1997-2004, and that in reality there was no bubble at all. Given the title of my doctorate at Oxford was called “The Economics of Ireland’s Housing Market Bubble”, you might not be surprised to learn that I disagree.

First, I think it is important to note that there are two ways of diagnosing bubbles. They can be thought of as statistical bubbles and economic bubbles. A statistical bubble is one where the growth rate in the price of an asset, such as housing, grows at a rate that is unsustainable for any reasonable period of time. Between 1995 and 2007, house prices in Dublin increased by 300% in real terms (i.e. stripping out inflation), or 12.2% a year. Between 1997 and 2004, McCreevy’s term in office, the increase was 136%, or 13.1% a year. (Nationwide figures are comparable, although slightly lower for the period as a whole, although not necessarily in every year.) Thus, by any statisticians metric, it was a bubble – put another way, if 12% growth had continued for 25 years, a house costing €100,000 in 1995 would have cost €1.7m by 2020.