The z-test is one of the most basic, and commonly used hypothesis tests. There are many data science interview questions on z-tests, so in this video we’ll dive into when to use it, and how to conduct both one-sample and two-sample z-tests for means.

Questions about Principal Component Analysis commonly appear in data science interviews. In this video, I’ll explain what principal component analysis is, how it works, the problems you would use PCA for, and the pros and cons associated with PCA.