University of Minnesota, Twin Cities
School of Statistics
Stat 3011
Rweb
Textbook (Wild and Seber)

# Stat 3011 (Geyer) In-Class Examples (Standard Deviation)

## General Instructions

To do each example, just click the "Submit" button.
You do not have to type in any R instructions (that's already done for you).
You do not have to select a dataset (that's already done for you).

**Non-Explanation:** In the famous words of a comment in the
source code for the UNIX kernel, "you are not expected to understand this".

What this code does is

- generate a random sample of size
`n` from the standard normal
distribution.
- plot its histogram, showing the sample mean and the sample mean plus or
minus one sample standard deviation.
- plot the density curve of the standard normal distribution, showing the
population mean and the population mean plus or
minus one population standard deviation.
- according to the "68%-95% rule" of the textbook, about 68% of the sample
lies between ticks on the horizontal axis on the upper plot. Maybe more, maybe
less than 68% depending on how representative the sample is.
- exactly 68.26895% of the population lies between the ticks on the
horizontal axis on the lower plot.