Both an open door and tight controls on foreign home ownership have dangers, but with no figures we can't have a debate.
Predictably, the debate over foreign interest in New Zealand houses has been muddied by accusations of racism against the Labour Party for its methodology. It concentrated on Chinese buyers because those were the names it could associate with ethnicity, or so it believes, and they made a disproportionate number of house purchases in Auckland sales data that the party has seen.
Labour's housing spokesman, Phil Twyford, believes this can be explained only by a large number of overseas buyers.
That is not the only possible conclusion. The fact that people with Chinese names appear to be buying proportionately far more houses than their proportion of the Auckland population could mean they are migrants in the investment category and each is buying a portfolio of residential property.
But Mr Twyford's explanation cannot be ruled out. He may have obtained his data surreptitiously from a single Auckland-wide agency, a demographic analysis based on surnames may be dubious, the political benefits of raising a hot-button issue may be obvious, but the figures he has obtained are of legitimate public interest.