Normal distribution properties

To access the normal distribution properties, open “descriptive statistics/details”

In addition to “the universality” of normal distribution, it is also very practical to characterize. The normal distribution equation is:

Equation normale

Only two parameters completely characterizing the distribution:

  • : average
  • : standard deviation

If these two parameters are known, then all the characteristics of the observed distribution are fully known.

This is what a normal distribution looks like with an average of 0 and standard deviation of 1:

From now on the normal distribution average and standard deviation will be noted.  This distribution can be perfectly defined since the two parameters are known: average and standard deviation.

To understand the normal distribution well it is good to know the following figures:

  • 27% of the actual values are located at + 1 of the average
  • 45% of the actual values are located at + 2 of the average
  • 73% of the actual values are located at + 3 of the average

Loi normale 2