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One of New Zealand's leading experts on gangs says gang statistics from police aren't suitable for use by politicians.
The figures were used on Wednesday by National Party leader Judith Collins to call for harsher action on organised crime across the country.
Canterbury University lecturer Dr Jarrod Gilbert told Morning Report the statistics work well for intelligence purposes, but not so much for policy.
Gilbert said it is easy for a person to get put on the gang list, but much harder to get off it.
"The list is growing very, very quickly, but it doesn't shrink correspondingly.
"So we can't rely on this data to say how big this scene is, or the degree to which the growth is occurring."
Listen to Gilbert here: