Their research was based on a biased sample (= a group of people/things containing more of one kind than normal, therefore not giving fair or accurate results).他们的研究基于有偏见的样本。
biased against somebody/somethingThe article was heavily biased against the current regime.这篇文章对现政权持有很大偏见。
biased towards/in favour of somebody/somethingThey admit that they're biased towards the Republican Party.他们承认偏袒共和党。