Learn in the textbookPrecision, Bias, and Various Biases
DefinitionPrecision and bias (精度と偏り) are separate views of measurement quality: precision is how small the spread of values is, and bias is how far they shift one way from the true value.
ExplanationPrecision is how closely repeated measurements of the same thing agree, and it rises as the spread narrows. Bias is how far the center of the measurements sits to one side of the true value, and it also goes by バイアス or systematic error (系統誤差).
AnalogyWhen arrows land in a tight cluster on a target, precision is high. How far that cluster sits from the bullseye is the bias.
Memory hookThe kanji 偏 appears in the Japanese words for picky eating and prejudice and means leaning to one side. The kanji 精 appears in the word for exactness and suggests fine, even detail.