ABSTRACT
All the tests, the authors have done so far assume that populations are distributed normally. The flying time of a pigeon is represented by a graphical method. The x-axis denotes the arrival time in minutes, which ranges from 1 to 35 minutes. The y-axis denotes the number of pigeons, which ranges from 1 to 11, with an increasing order of 1. A fundamental theorem in statistics is the central limit theorem (CLT). Sometimes, measurements from a sample that are not normally distributed would be normally distributed if the measurements were transformed in a specific way. For instance, the example at the beginning of the lesson can be ‘made more normal’ with the use of logarithms. Typically, a non-parametric test is based on ranks: that is, the order of the values rather than the values themselves. There exist non-parametric tests analogous to all the tests already seen.
