
Unbiasedness, Bias & Mean Squared Error (MSE)
Build a rigorous understanding of unbiasedness, bias & mean squared error (mse) through 25 original single-select and multiselect questions. Begin with core definitions, then work through calculations, assumptions, counterexamples and advanced diagnostic challenges. Prerequisites: the earlier core Statistics curriculum, including probability distributions, expectation, calculus and the preceding mathematical-statistics sets. Competencies: Distinguish estimators, estimates and bias; Prove unbiasedness of means and sample variance; Derive the MSE bias-variance decomposition; Compute risk and compare biased and unbiased estimators; Distinguish known and estimated mean variance formulas; Study shrinkage and parameter-dependent risk; Relate MSE consistency to probability convergence; Identify fourth-moment requirements for variance-estimation risk. Every item includes a worked explanation and reasons for rejecting distractors. Further reading: [Scalar bias-variance decomposition](https://www.statlect.com/glossary/mean-squared-error), [Unbiased and biased sample variance](https://www.statlect.com/glossary/sample-variance), [Point estimation, bias and risk](https://hanbaeklyu.com/wp-content/uploads/2020/10/lecturenote_170s.pdf).
Oct 26, 2026










