Selection Bias
Sampling Bias
The selection of individuals, groups or data for analysis in such a way that proper randomization is not achieved, thereby ensuring that the sample obtained is not representative of the population intended to be analyzed.
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Origin
Selection bias emerged as a recognized methodological concern in survey research and experimental design during the mid-20th century as statistical theory matured. A seminal 1982 study examining 50 R&D teams formalized understanding of how non-random selection distorts results. The concept became fundamental to research methodology, encompassing sampling bias, attrition bias, and self-selection bias. Randomization techniques were developed specifically to mitigate these systematic errors.
Updated February 22, 2026