The Sensible Sentencing Trust is dubious of figures touted by the Justice Minister in a restorative justice funding announcement.

Amy Adams announced a $16.2 million increase in funding to help restorative justice providers yesterday.

She touted data from 2008 to 2013, which she said shows the reoffending rate for those who've done restorative justice is 15 percent lower than offenders who didn't.

That's over the 12 months following the programme, and accounts to about 26 percent fewer offences per offender.

But Sensible Sentencing's Jock Jamieson said the figures have been manipulated to make the outcomes look far better than they actually are.

He said the figures don't mean anything, because she's talking about repeat offenders.

"The chances of a recidivist offender engaging in the restorative justice conversation with a victim and being changed by that are really quite slim. If they're first time offenders we might believe them," he said.

"I actually have doubts that Amy Adams herself actually came up with those figures. I think someone has put them down in front of her and she perhaps signed it off.

"Perhaps if she looked at it again, she might want to reissue her statement."