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).

The Normal Distribution

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.