A leading criminologist is sceptical about claims crime statistics have been manipulated.

Outgoing police association president Greg O'Connor told TVNZ's Q and A programme statistics showing a drop in crime have been manipulated.

Mr O'Connor said inaccurate statistics from the Police Commissioner were skewing the conversation about whether police should be armed or not

University of Canterbury criminologist Greg Newbold says Mr O'Connor may be just as guilty of manipulating the statistics.

"Greg is a great advocate of arming the police so he's going to pick out statistics which show that it is a problem and the Commissioner who would be against arming police is going to use statistics which show that guns aren't a problem."

Newbold thinks Mr O'Connor may be skewing the statistics in order to get police armed.

'You can pick whatever statistics you like to say whatever you want them to say, but the fact is as far as mortal crime, as far as lethal offending is concerned guns are less of a problem than they were in the nineties."