The Earthquake Commission has admitted that about 31,000 claims have been unintentionally excluded from customer surveys in the past three years.
Its chief executive Ian Simpson says an internal check confirmed the presence of an automated flag in the claims management system which meant customer claims were not included in the sample for its quarterly nationwide satisfaction survey.
The 'do not survey' flag is present on about 31,000, out of 154,000 claims.
Mr Simpson says he has asked for the use of the flag to be reviewed.