The Social Development Ministry has removed all its statistics from the Child, Youth and Family website after errors were detected.
It says a system upgrade has resulted in some data not being collated properly.
The ministry says the whole statistics section of the website has been removed but is likely to be put back up by the end of the month.
It says key indicators such as family group conferences, which are measured by an external system, have been affected.
The ministry says an upgrade to that system in 2011 has resulted in some data not being counted.
It says the errors have only just been picked up, after an analyst spotted a discrepancy between two sets of data.
It is confident the incorrect data is not significantly different from the correct figures.