Don't talk to me about being 'unbias' or I will thump you hard with the nearest available object. The correct adjectival form is 'unbiased'. Similarly, if you display a bias against something, that means you are biased.
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I genuinely don't know why people find this particular rule hard to grasp. Perhaps the offenders aren't listening carefully. The error pops up frequently in writing of all kinds. Here's the New Zealand Herald earlier this month:
Cooper insists that his advice is independent and unbias.
Incidentally, the Macquarie Dictionary does not include 'unbias' as a verb meaning "to remove bias", which is a usage some online dictionaries suggest is OK. But even if you find that pseudo-verb acceptable, it wouldn't change the fact that "unbiased" and "biased" are the correct adjectival forms. All the morons who have littered the web with the phrase "don't be bias" need to realise they are mistaken.
Lifehacker's Mind Your Language column offers bossy advice on improving your writing.