Chapter 3 – clarity on ppf

[n-splv]

There is an issue on chapter XXX, in the following paragraph

The function ppf in python gives us the inverse of the CDF. Instead of multiplying the standard error by 2 like we did to find the 95% CI, we will multiply it by z, which will result in the 99% CI. So, ppf(0.5) will return 0.0, saying that 50% of the mass of the standard normal distribution (mean 0 and 1 standard deviation) is below 0.0. By the same token, if we plug 99.5%, we will have the value z, such that 99.5% of the distribution mass falls below this value. In other words, 0.5% of the mass falls above this value.

For clarity, I would add:

, and subtracting 0.5% from each side gives us exactly the 99% confidence interval.