Published online by Cambridge University Press: 13 March 2020
Why you care: What is the point of running an experiment if you cannot analyze it in a trustworthy way? Variance is the core of experiment analysis. Almost all the key statistical concepts we have introduced are related to variance, such as statistical significance, p-value, power, and confidence interval. It is imperative to not only correctly estimate variance, but also to understand how to achieve variance reduction to gain sensitivity of the statistical hypothesis tests.