We usually use the word “bias” when we’re talking about prejudice. We know that a biased news article or a biased professor judges a topic or a person unfairly.
But, in this context, we’re looking for something slightly different. In a systematic review, when we assess for risk of bias, we’re looking for evidence of deviation from the truth.
Essentially, we want to know: what’s the likelihood that the way the study was conducted led to incorrect findings?