Rare and Common
How normal is normal? This app gets students to contrast their everyday notion of 'normal' to the distribution of the same name.
Common, uncommon, and rare
Using the z-score to express everyday concepts of common and rare.
Shapes of distributions
Introduces terms such as skew, bi-modal, and flat, by reference to the difference of the actual variable from a theoretical normal distribution.
Parameters of the normal distribution
Normal distributions are a *family*. The specific members of the family are identified by two parameters: the mean and the standard deviation.
Comparing two confidence intervals
Using plain confidence intervals on the mean to decide if there's good evidence that the means are different.