Residents relying on Neighbourhood Watch crime statistics in their suburbs could be left with the impression crime is much lower than is otherwise reported by police.
Analysis undertaken by Fairfax Media compared data for each category of crime provided to Neighbourhood Watch over a five-year period with ACT Policing crime statistics published quarterly.
In one year the rate of burglary for one suburb was 180 per cent higher than was reflected in the Neighbourhood Watch statistics.
More than 30 Neighbourhood Watch groups in the ACT distribute supplied crime data, from ACT Policing, to thousands of households.
About 25 per cent of burglaries didn't show up in statistics provided to Neighbourhood Watch in Ainslie from 2011 to 2013.
Over a four-year period across Canberra from 2011 through 2014, more than 10 per cent of all motor vehicle thefts did not appear.
Two in every five assaults in the entire Belconnen region were not reflected in Neighbourhood Watch statistics in 2013.
That same year almost two-thirds of all burglaries in Wanniassa did not show up in Neighbourhood Watch reports to residents.
The analysis raises questions about which data set most accurately reflects crime in the territory and whether residents receiving Neighbourhood Watch letters are being led to believe crime rates are lower than what appears on the ACT Policing website.
Neighbourhood Watch publicity officer and board member Julian Fitzgerald said the organisation would be extremely concerned if erroneous police crime statistics were being disseminated in suburban Canberra.
"The board will meet to discuss the important issue of the integrity of this information and no doubt seek a clarification from the minister to urgently conduct a review into why this data cannot be relied upon," he said.
The big difference between crime statistics Neighbourhood Watch were dropping into letterboxes and those published by ACT Policing on its website quarterly was explained by different "counting rules".
An ACT Policing spokeswoman said differences in counting rules were used to extract statistics for each purpose.
"These counting rules would have been discussed with Neighbourhood Watch when the data was first provided to them," she said.
"The statistics provided to Neighbourhood Watch only show the most serious offence per location, for each month.
"This is to avoid duplication, in order to provide the most useful overview of neighbourhood crime for this purpose."
"These counting rules are similar to counting rules used in the Australian Bureau of Statistics crime publications, such as Recorded Crime – Victims and Recorded Crime – Offenders annual reports."
Australian Institute of Criminology spokesman Colin Campbell said it appeared ACT Policing had created a subset of incidents more directly relevant to the work and aims of Neighbourhood Watch.
"It would not be uncommon for a data holding agency to use and report different extracts from the overall dataset for different purposes," he said.