# Lesson 32: Confidence Intervals for Variances

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.