England's exams watchdog hired consultants to come up with alternatives to the word "error" amid concerns it had negative connotations, it was disclosed today.

Ofqual also admitted it had "shied away" from talking about reliability in testing due to fears about negative headlines damaging public confidence.

The regulator was established by ministers to improve and maintain public confidence in qualifications and assessments.

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It said it aimed to "encourage debate" about topics such as standards.

In a speech to the International Association for Educational Assessment conference in Brisbane this week, Ofqual head of standards Dennis Opposs said: "Why have we previously shied away from communicating much about reliability in public?

"Well it is a complex idea that is hard to explain. We have worried in the past that negative news stories about it could damage public confidence.

"On the other hand shouldn't assessment organisations be transparent and communicate with the public about measurement inaccuracy?"

Mr Opposs said the watchdog had paid communications consultants Blue Rubicon to produce "a narrative for Ofqual staff to use when speaking about reliability and unreliability".

As part of this work they were instructed to come up with suitable replacements for the word "error" to describe discrepancies in exam marking.

A report presented by Mr Opposs at the conference said: "It was necessary to choose an alternative term to 'error' as this was too closely associated with culpability, and because it had an unhelpfully subtle word grammar."

The word "variation" was chosen as the best alternative, ahead of suggestions including variance, uncertainty, discrepancy, inconsistency or clash.

The report says: "'Clash' is probably not close enough in meaning to unreliability and also has the potential to provide incendiary headlines."

There have been continuing concerns in recent years about the reliability of marking in public exams and school tests.

Ofqual chairman Kathleen Tattersall has said previously that the public still have "unrealistic" expectations of England's exams system, and must realise there will always be human error involved in marking.