Bias Definition: What Bias Means and Where It Shows Up

The meaning of bias, by setting

1. Everyday judgment. Favoring or disfavoring someone without a fair reason. "The judges showed a clear bias toward the older singers."
2. The mind. A built-in shortcut in thinking that tends to lead people astray, called a cognitive bias. Confirmation bias, for example, is noticing facts that fit what you already believe and missing those that do not.
3. Research and statistics. A systematic error that pushes results one way, such as surveying only people who answer phones during work hours.
4. Law. A reason to think a judge, juror or official cannot decide a case fairly, for example because they know one side.
5. Sewing. The diagonal direction across woven fabric. Cloth "cut on the bias" stretches and drapes more.
6. Electronics. A steady voltage or current applied to a part so it works in the right range.

Bias in sentences

• The teacher asked a colleague to grade the essays too, to avoid any bias toward students she knew.
• Critics said the survey had a sampling bias because it only reached city residents.
• I'll admit my bias: I grew up in that neighborhood, so I love its food stalls.
• The dress was cut on the bias, so it hung softly from the shoulders.
• Don't let one bad experience bias you against the whole company.

Bias in grammar: forms and prepositions

As a noun, bias takes the prepositions toward, in favor of and against: "a bias against new ideas". You can have a bias, show a bias, admit a bias or correct for a bias. The plural is biases.

As a verb, to bias something is to influence it unfairly: "The wording of the question may bias the answers." The adjective biased describes a person, report or result that is not neutral, and unbiased is its opposite. Note that biased is the standard spelling in the US and India; British writers sometimes double the s.

Bias definition compared with prejudice and discrimination

Bias is the widest of the three. It lives in thinking and can be about anything, even a favorite brand of tea. Prejudice is a stronger and usually social attitude. Discrimination is what happens when bias or prejudice turns into unfair treatment.

From bowling greens to the mind

The earliest English bias, from the 1520s, was an oblique or diagonal line, from French biais, a slant. Where the French word came from is not known for certain. In the 1560s, players of the old lawn game of bowls used bias for a ball weighted on one side so that it curved instead of rolling straight. In the 1570s it shifted into the mind: a one-sided leaning. Early uses in law already meant an undue leaning toward one side.

Conscious and unconscious bias

People often separate explicit bias, which a person knows about and could state, from implicit or unconscious bias, quick associations a person may not be aware of. Many workplaces and schools run training on the second kind. Researchers and commentators debate how well such bias can be measured and how much training changes behavior, so you will see the topic discussed from several angles in the news.

Because bias can enter a court case, legal systems have rules that let a judge or juror be replaced if there is a real risk they cannot be fair.

Related ideas: perception and cognitive. Neighboring ideas such as justice and equality have pages of their own, listed among our civic and legal words.