# Lesson 32: Confidence Intervals for Variances

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Hey, we've checked off the estimation of a number of population parameters already. Let's check off a few more! In this lesson, we'll derive (1−α)100% confidence intervals for:

(1) a single population variance:  $\sigma^2$

(2) the ratio of two population variances:  $\dfrac{\sigma^2_X}{\sigma^2_Y}$  or  $\dfrac{\sigma^2_Y}{\sigma^2_X}$

Along the way, we'll take a side path to explore the characteristics of the probability distribution known as the F-distribution.