Resist panic but put away the champagne. That's the NSW Education Department's message to schools, warning that glitches in NAPLAN data to be released this week – mean surprise boosts or dips in results should be treated with caution.
Student reports will begin arriving from Thursday, but this year's data comes with a caveat because a fifth of NSW students did a new form of the tests online and the rest used pen and paper.
Murat Dizdar, deputy secretary of the NSW Department of Education, said parents could trust the report for an accurate snapshot of their child's performance, but the data was less reliable for inter-school comparison.
"We've seen some of our schools where the trend line for let's say, writing or reading for a particular year group may have been tracking in one direction, and there's been a sudden up spike or down spike in performance," Mr Dizdar said.
"We've said, 'treat your data with care this year, until everyone is doing the online format'.
"Don't make any sudden changes in what your literacy and numeracy programs look like because of this year's data. If they've had a massive improvement, now is not the time to stand on the podium and wait for a gold medal.
"At the national level ... we are comfortable that it is comparable."
The new online test, which will entirely replace the written version in 2020, adapts to ability; if the student gets the first few correct, the questions get harder, leading to a more detailed assessment of their ability.
The Australian Curriculum, Assessment and Reporting Authority (ACARA) admitted there were some differences in student performance between the two types.
Results in grammar and punctuation, Year 9 numeracy and Year 7 reading were scaled so they could be compared, but in Year 9 writing the online cohort scored an average of nine points (out of 1000) higher than those using pen and paper.
Mr Dizdar said some of the discrepancies in this year's results could be due to the introduction of the online test, but some could be caused by other things, such as an unusually strong cohort.
Department officials would help schools work out the influences behind unexpected changes.
Maurie Mulheron from the NSW Teachers Federation has written to ACARA asking for more detail about how it equated the results.
"We want them to be honest instead of justifying the results as though there's no controversy," he said. "All these processes are happening behind closed doors. Because there's a lack of transparency, there's a lack of trust."