### Quick Question

If you want to know the mean value of a numerical variable, which function could you use?

Explanation If you using the summary function (in the video, we typed summary(WHO) in our R console) you can see a statistical summary of each variable. For numerical variables, the mean value is listed.

If you want to know the standard deviation of a numerical variable, which function could you use?

Explanation Neither the str function nor the summary function provides the standard deviation value of a variable. We'll see how to compute this value in the next video.