There's revelations a rise in top grades at universities may not be down to New Zealanders getting smarter.

Analysis by the New Zealand Initiative reveals 'A ' grades have increased from 22 percent to 36 percent of all grades since 2006.

B grades have fallen from 47 percent to 38, while C grades have dropped from 20 percent to 17.

NZ Initiative research fellow Dr James Kierstead says 'A' grades are becoming the most common grade for university assignments and that shouldn't be the case.

"It's not really something we want to follow the US in, because grade inflation's been a big deal in the states and it's helped undermine half a dozen universities there."

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