This is a introduction to fundamental statistics, and not a very instructive one. For example, this is incorrect:<p>&quot;By definition, one standard deviation is the amount of variance within a set of measurements that encompasses approximately the top 68 percent of all measurements in the data set; in other words, knowing the standard deviation of your data set tells you how densely the data points are clustered around the mean.&quot;<p>The 68% refers to a rule of thumb for normal distributions, not the definition of standard deviation.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Standard_deviation" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Standard_deviation</a><p>Also, applying this rule will get you in big trouble if your data happens to have a mean that&#x27;s less than zero:<p>“Data with a standard deviation greater than half of its mean should be treated as suspect. If the data is accurate, the phenomenon the data represents is not displaying a normal distribution pattern.”