New Zealand's prediction market, iPredict Ltd, says yesterday's announcement by Police Minister Judith Collins that Peter Marshall will be the next Police Commissioner is further evidence of the market's prediction power.

The prediction market correctly forecast that neither Deputy Commissioner, Viv Rickard or Rob Pope, would get the top job.

"We launched the contracts expecting like most observers that there would be a two horse race between the Deputy Commissioners, but the market very quickly put us right," the chief executive of iPredict, Matt Burgess, said today.

"For virtually the entire run of the contracts, between 9 September and today, the contracts for Mr Rickard and Mr Pope traded at very low prices, while the price for the "Other" contract traded at a high price."

The three contracts - Rickard, Pope and Other - formed a bundle which traded for a total price of almost exactly $1 through the three months.

"We don't know who traded on the contracts, but the forecast was plainly influenced both by people making their own assessments of the sorts of candidates the police would prefer and later by people with insight into the appointment process," Mr Burgess said.

"This is how iPredict works under the rules set for us by the Securities Commission and is why prediction markets achieve such high rates of predictive power," he said.

iPredict is owned by Viclink, the commercial arm of Victoria University of Wellington, and operates with authorisation from the Securities Commission. Details on the company and the stock can be found at www.ipredict.co.nz.