Définition Approximation

In statistics, many results are only approximate; meaning they are similar but not equal to the actual result. An approximation can turn a complex calculation into a less complicated one.

For instance, the calculation of a Poisson distribution is more complicated than that of a binomial distribution. If both only differ slightly in their end result, it is permissible to approximate the Poisson distribution by a more simple-to-use binomial distribution. Prerequisite for such approximations is a sufficient sample size. In this example, at least 100 respondents are necessary in order to justify a sufficient proximity of the two distributions. An approximation based on too small a sample can lead to errors – for example, an accidental similarity of the two distributions.