When I use a word . . . Defining bias in research

The original definition of the word “bias,” when it entered the English language in the 16th century, was a diagonal line, and specifically one that cut across the warp or weft of a woven fabric. It later came to mean the tendency of a bowl, the asymmetrically shaped ball-like object used in the game of bowls, to take a curving course when rolled across a lawn, and eventually, among other things, something that produces distortion of a statistical result. Based on a study of its etymology, usages, previous definitions, and sources, I propose the following definition of a bias in research: <b>bias,</b> n. /ˈbʌɪəs/ A systematic distortion, due to a design problem, an interfering factor, or a judgment, that can affect the conception, design, or conduct of a study, or the collection, analysis, interpretation, presentation, or discussion of outcome data, causing erroneous overestimation or underestimation of the probable size of an effect or association [ancient Greek ἐπικάρσιος, crosswise, esp. at right angles, via French biais] This defines the count noun, a bias. The non-count noun, bias, could be defined as a tendency to produce biases.