Archetype Definition: a common character, image, symbol, or situation that occurs in literature and in life, and considered to be universal across most cultures. Archetype examples are found in the world around us every day: in our speech, our beliefs, media, sports, video games, psychology, art, and even our dreams. Archetypes are universal; that is, they occur across all cultures, religions, and parts of history.
The above plot illustrates Poisson probabilities for Î» = 7.5. and this plot illustrates Poisson probabilities for Î» = 15. The mean of the Poisson distribution is Î». For the Poisson distribution, the variance, Î», is the same as the mean, so the standard deviation is âÎ». Empirical tests. There are also some empirical ways of checking for a Poisson distribution. 1  The simplest and handiest way is to see if the variance is roughly equal to the mean for your Poisson data.
Standard Deviation and Variance A commonly used measure of dispersion is the standard deviation, which is simply the square root of the variance. The variance of a data set is calculated by taking the arithmetic mean of the squared differences between each value and the mean value.he population standard deviation is the square root of this value. The variance of a sampled subset of observations is calculated in a similar manner, using the appropriate notation for sample mean and number of observations.