The HSC is an "artefact of the past" that should be scrapped, according to a leading NSW Catholic educator who warns that NAPLAN data is often misused and misrepresented and should not be linked to year 12 results.

Greg Whitby, the director of Catholic education in the Parramatta diocese which has more than 45,000 students, said the HSC was a relic of the 1950s and no longer reflected the needs of young people entering a rapidly changing workforce.

"The HSC has had its day. The current HSC is rarely used to seek employment and only 20 per cent of students use their ATAR to get into university," Mr Whitby said.

"When you have students around the world doing MOOCs online (massive open online courses) and are designing their own degrees, there is no doubt the credential is going to have to change otherwise all we are doing is looking backwards."