Auckland's recent house price rises have been unprecedented, up 52 per cent in the last four years compared with elsewhere up only 11 per cent.
A Reserve Bank Bulletin out on Friday described the magnitude of change, saying that since mid-2012 prices had risen at a pace not seen before compared with other areas of the country.
The ratio of Auckland house prices to those in the rest of New Zealand has risen since 1981. The extent of that increase since 2009 was never seen in New Zealand before, the bank said.
An upward trend might be expected over time, but it is not clear how steep that trend should be, whether it is time-varying, or whether it will persist.
"New Zealand house prices have risen significantly over the past five decades. In real terms, house prices have more than tripled, with a strong upward trend since 1994. Nonetheless, there have been several instances where real house prices have fallen.