Australian education officials are in a stand-off that is delaying the release of NAPLAN results.

The stoush had emerged from the fact that data from the online literacy and numeracy test is not statistically comparable with the pen-and-paper test.

This means there can be significant divergence in grammar and punctuation between students who sat the online test and those who took the written version.

The adaptive online test becomes easier or more difficult depending on whether students answer questions correctly.

Report sat students who perform well in the online reading test are given more difficult questions in the grammar and punctuation test.

Students taking the tests online also do not receive the so-called “confidence building” questions  that their pen-and-paper peers get.

So, top-performing students in schools that take the test online risk receiving lower marks than those who sit the written version.

University of Melbourne expery Professor Patrick Griffin says the online test is superior because it provides teachers with more detailed, robust information.

“On the pen-and-paper test there are very few question for the upper and lower levels which means you have less information about the student’s ability and what they are ready to learn,” he told Fairfax.

He said it is “almost impossible” for students to hit a ceiling with the adaptive, online test.

Additionally, many students who sit the online test write much longer essays than those working with pen and paper.

The people marking the online tests have the additional duty to discern spelling mistake from typo, by looking to see if the same word is spelled correctly elsewhere in the exam.

Another concern is that students who are reliant on auto-correct can miss more grammatical errors, lowering their scores.

Preliminary national results were due to be released on Friday, but they will now wait pending a meeting between state and federal education ministers. The ministers will try to release the results in a form that addresses some of the concerns between the different NAPLAN tests.