"Calculating Mean and Standard Deviation" section shows incorrect values

[Augusto Claro]

The shown avarage variance is 254.23, but the correct one would be 228.81.

the sum of variances is 2288.1 and seems like it's dividing by 9 (to have 254.23) instead of by 10 (the correct length of the array, which will give us 228.81).

[Luke Nonas-Hunter]

This confusion come from the difference between Population Standard Variance and Sample Standard Variance.

In the book, Shiffman is using Sample Standard Variance (254.23). However the 228.81 comes from Population Standard Variance.

I found this article to be very helpful in describing the difference: click here

[Cameron Smith]

Looks like this issue was corrected as a part of #65 🙂

[Daniel Shiffman]

Thanks everyone for the comments! Closing this issue, feel free to flag it in noc-book-2