For Wikipedia's policy on avoiding bias, see Wikipedia:Neutral point of view.

Bias has several different meanings, most relating to an offset or prejudice of some sort.

Viewpoint

A bias is a prejudice in a general or specific sense, usually in the sense for having a predilection to one particular point of view or ideology. One is said to be biased if one is influenced by one's biases. A bias could, for example, lead one to accept or not-accept the truth of a claim, not because of the strength of the claim itself, but because it does or does not correspond to one's own preconceived ideas.

For example, having an Americo-centric point of view (that is, the point of view of an American, in particular one from the US) is a bias, as is having a particular point of view of any other country.

In practice, accusations of bias can also result from unacknowledged bias on the part of the critic. If a critic takes their own preexisting view as a priori balanced without acknowledging their own potential biases, any person or organization that disagrees with it is automatically viewed as biased regardless of that person or organization's actual efforts at balance. This is particularly common in discussion of media outlets such as CNN, Fox News Channel, The New York Times, The Globe and Mail, the National Post, etc. (For example, Bill O'Reilly has made accusations of liberal bias against the staunchly conservative Globe and Mail, while people that disagree with O'Reilly accuse him of bias.) Note that this does not necessarily mean that these media outlets don't have identifiable biases, but only that when evaluating claims of bias, one should always take the political viewpoint of the critic into account as well. (See also objectivity.)

A systematic bias is a bias resulting from some system.

Statistics

In statistics, the word bias means that an estimator for some reason on average over- or under-estimates what is being estimated. It has at least two different senses, one referring to something considered very undesirable, the other referring to something that is occasionally desirable. Example include:

• confirmation bias
• publication bias
• selection bias
• recall bias
• response bias

Science

In philosophy of science and design of experiments, bias comprises psychological factors which affect scientific hypothesis testing. Widely recognised variants include:

• culture bias
• cognitive bias
• confirmation bias
• infrastructure bias
• perception bias
• notation bias

Electronics/electrical engineering

In electrical engineering, the term bias has the following meanings:

1. A systematic deviation of a value from a reference value.
2. The amount by which the average of a set of values departs from a reference value.
3. Electrical, mechanical, magnetic, or other force (field) applied to a device to establish a reference level to operate the device.
4. In telegraph signaling systems, the development of a positive or negative DC voltage at a point on a line that should remain at a specified reference level , such as zero.

Note: A bias may be applied or produced by (i) the electrical characteristics of the line, (ii) the terminal equipment, and (iii) the signaling scheme.

(Source: from Federal Standard 1037C and from MIL-STD-188)

Most often, bias simply refers to a fixed DC voltage applied to the same point in a circuit as an AC signal, frequently to select the desired operating response of a semiconductor (forward or reverse bias). For example, a bias voltage is applied to a transistor in an electronic amplifier to allow the transistor to operate in a particular region of its transconductance curve.

Bias is also the term used for a high-frequency signal added to the audio signal recorded on magnetic tape. See tape bias.

Bias is used in direct broadcast satellites such as DirecTV and Dish Network, the IRD box actually powers the feedhorn or LNB receiver mounted on the dish arm. This bias is changed from a lower voltage to a higher voltage to select the polarization of the LNB, so that it receives signals that are polarized either clockwise or counterclockwise, thereby allowing it to receive twice as many channels.

Computer Science

Bias is often used to describe how a search algorithm is restricted or expects the world to behave. For example, it could be biased by restricting the search space, or by assuming the heuristics such as Occam's razor are applicable to the world.

See also

• Neutral
• Scholarly method