2/16/2022

Return to calculations for normal distributions (from class on Monday)

Assessing Normality

• Should we use the normal model for a given data set?
• 68-95-99.7 Rule
• Normal Quantile Plots - qqnorm in R
• Other Visual Displays

Class Activity on using qqplots to assess Normality

• Open the R script QQPlot.R to conduct simulations that will help you develop your understand of these new plots.
• The script simulates data from normal distributions, uniform distributions, and t distributions. Look at the histograms and qqplots carefully. You can run the commands multiple times to help you distinguish general trends from chance variation.
• Describe each of the plots. Can you explain how the differences in the distributions are appearing on the normal probability plots?
• Use appropriate methods for assessing normality to see if the normal distribution would be an appropriate model for the qunatitative variables from our Data Survey on Day 1.

Please read Section 4.3 for class on Friday.