A computer error in primary school assessment results led to teachers being given false information about the performance of their pupils.
It comes just weeks after another blunder in which pupils at more than 300 schools were told they had received incorrect test scores.
Education Minister Caitriona Ruane has said the latest lapse highlighted to schools the danger of trying to introduce a system of testing that had not been trialled.
The InCAS (Interactive Computerised Assessment) came under fire yesterday when it was announced that a second mistake had been detected in the standardised scores that had been sent to schools.
The system is used to evaluate whether children are at the expected standard in subjects like maths and reading.
These standardised scores are used by some schools to determine how pupils perform relative to other pupils and were not intended for reporting to parents.
The mistake was noticed when principals at nine different schools contacted examinations body CCEA and raised concerns over some of the information they had received. The CCEA said it was contacting all the schools involved to inform them of this further error and issued an apology.
It said it had no plans to stop the contract with the centre for Evaluating and Monitoring (CEM) at the University of Durham, which administers the InCAS system.
“We want to make sure that it does not undermine the confidence in the InCAS system as it is very valuable for teachers and schools in assessing the potential of the pupils,” said Neil Anderson, chief executive at CCEA.
“We have been very pleased with the service they have provided us with until now and we have had their assurances that the error has been detected and fixed.”
Ms Ruane said: “These incidents should highlight to all schools the danger of trying to implement a system of testing young children using breakaway tests that have not been validated or trialled.”
An error relating to the computer based InCAS assessment tool for general maths earlier this month led to incorrect |results being sent out to more than 300 primary schools across Northern Ireland.
The assessment is used to support schools in identifying pupils’ strengths and areas where they are having difficulties. The results had already been processed and sent out to parents by 79 of the schools affected.
The error was caused by a blip in the computer programme and CCEA were assured that this had been fixed.