Rather than comparing NAPLAN outcomes across similar schools, MySchool now compares student performance to a projection of their expected performance based on their background.

The parental occupation and education, Indigeneity and geographic location of students is used to determine how they should be expected to perform on NAPLAN.

Berry said that this method does not work in the ACT.

“The ACT has a predominately public service workforce where many people hold the job title ‘manager’ across a range of employment classifications. 65 per cent of ACT students have a parent with a bachelor’s degree or above, compared to the national average of 35 per cent,” Berry said.

“These two factors together artificially increase predicted NAPLAN scores. Comparing the predicted and actual scores results in a large difference that falsely suggests underperformance of ACT schools, both government and non-government.

“There is also a problem with establishing meaningful statistical prediction for the ACT because of the relatively small number of schools and students.

“The change to how ACARA compares results between schools has meant that the data comparisons released today for ACT schools are even more unreliable and invalid than in previous years.”

The ACT has generally performed very well on NAPLAN, but since the MySchool website was redesigned, many schools now appear to be performing below expectations.

“ACARA, other states and territories, and education data experts agree that there are anomalies in the ACT data,” Berry said.

“With the support of all states and territories and the federal government, ACARA will seek expert advice to review the approach adopted for NAPLAN comparisons this year. Until this review is completed and the flaws corrected the comparisons cannot be relied on as a measure of the ACT's NAPLAN performance.”

Several senior education figures praised the redesigned MySchool website yesterday.

Australian Council of State School Organisations president Andrew Bidwell thanked ACARA for listening to feedback about the site.

“Parents have been asking for a simpler site with focus on student progress instead of direct rankings, and this change promises to deliver,” he said.

“ACSSO welcomes our ongoing partnership with ACARA to provide the best outcomes for Australian parents.”

Australian Parents Council president Jenni Rickard said the new website was “a big improvement”.

“It now provides more of the kind of information parents want to know, with a new layout, graphics and language that are much more parent friendly,” she said.

“The focus on how much students have improved, especially the new comparisons to similar students, also gives parents a simple way to see how well their child's school is going.”

ACARA held focus groups with parents around the country while developing the new site.

"The schools that they were interested in comparing were usually only ... a handful of three or four in their local area and they don't lose that capability from the changes that we've made," ACARA head David de Carvalho said.