Learn in the textbookPrecision, Bias, and Various Biases
DefinitionStatistical bias (統計的バイアス) is the umbrella term for systematic skew in which the way data is collected or measured pushes results away from the true value in one direction.
ExplanationThe whole group you want to know about is the population (母集団), and the part you actually examine is the sample (標本). When a sample is used to infer the population, any shift caused by the survey method is statistical bias, and selection bias (選択バイアス) and information bias (情報バイアス), for example, are kinds of it.
AnalogyA clock running five minutes fast is off in the same direction every time you look. Checking it more often brings you no closer to the right time.
Memory hookThe English word bias originally meant a slant. A ball on a tilted table rolls to the same side however many times you release it.