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Sample variance estimator is a easy quant interview question on stats & data analysis.
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This is an easy foundational question in statistics that quant firms use to verify you understand a critical distinction in estimation theory. It asks you to identify the correct normalisation constant for an unbiased estimator of population variance when working with sample data.
The question probes whether you know why the denominator in the sample variance formula differs from what naive intuition might suggest. This distinction arises because of the relationship between bias, degrees of freedom, and the use of the sample mean as a plug-in estimator. Understanding this concept is essential for anyone working with empirical data in trading, risk, or research roles.