So how, exactly, did the errors occur?
Two errors were discovered in the coding process or algorithm used to implement the standardisation process affecting the results of at least 6,500 students.
This standardisation process adjusted teachers’ estimated grades up or down for reasons of consistency based on a number of factors.
The first error was in a line of code programmed by Canadian firm Polymetrika International Inc.
The error affected the way in which candidates' Junior Cycle results were used in the standardisation process.
A second error also related to Junior Cycle: it involved the use of results for a subject – Civic, Social and Political Education (CSPE) – that were not supposed to have been used in the first place.
Why were Junior Cycle results being used in the first place?
These results were used to build a picture on the likely collective performance of an individual class in the Leaving Cert.
The team behind the calculated grades model concluded that Junior Cert exam results were strong predictors of Leaving Cert performance, but were inadequate by themselves to estimate individual student performance.
However, because of their near-universal coverage, they felt they provided a useful means of determining the objective performance of classes and schools.
So, how did the errors impact on students’ final results?
It was intended that the students' aggregate Junior Cycle results in Irish, English and maths would be included in the data used by the national standardisation process, together with their two best other subjects.
However, the error meant students' results in their two weakest subjects ended up being used.
As a result, in some subjects, students received calculated grades that were lower than they should have been and some received grades that were higher.
Was that the only error?
No. A second error was discovered while performing checks related to rectifying the first error.
It meant Junior Cycle results for the subject CSPE were included in error in the data mentioned above. This subject was not supposed to be used in the standardisation process. This also impacted on some students’ grades.
How were these errors uncovered in the first place?
Minister for Education Norma Foley said this week that Polymetrika discovered the error on Tuesday night of last week and alerted the Department of Education shortly afterwards.
Officials say the error was discovered when data for the Leaving Cert Applied grades were being processed.
So, how many have been affected, exactly?
The precise number of students who will receive higher grades will not be available until a series of verification checks are completed. This will likely take until the end of this week. However, the department says its likely to be in the region of 6,500.
The majority of students will be moved up a single grade, which at higher level is the equivalent of about 10 CAO points.
No student will receive a reduced grade in any subject as a result of this process.
Why were just 6,500, or 10 per cent, of students affected?
We don’t know yet for sure. It is likely that either the coding errors affected a subset of classes or schools; it is also possible that the errors affected the marks of all students – but only enough to change the grade in 6,500 cases. Again, we don’t know for sure yet.
Could there be further errors?
The errors we know about are being rectified. The department says it has carried out a series of further checks and has identified no further errors in the coding.
As a further step, it has contracted ETS Educational Testing Service, a US firm which specialises in educational measurement, to review essential aspects of the coding.
It says the results data have now been re-run through the corrected model. The review of relevant aspects of the code by ETS is expected to take a number of days. Once this is completed, the department will have full information on which students will benefit from the improved grades and the specific subjects involved for each student.
