Kurtosis Formula For Ungrouped Data. N is the total number of observations. Therefore sample kurtosis equals.
For a sample of n values a method of moments estimator of the population excess kurtosis can be defined as where m 4 is the fourth sample moment about the mean m 2 is the second sample moment about the mean that is the sample variance x i is the i th value and is the sample mean. Therefore sample kurtosis equals. S sample standard deviation.
S sample standard deviation.
The kurtosis can also be computed as a4 the average value of z4 where zis the familiarz score z x x σ. Thus with this formula a perfect normal distribution would have a kurtosis of three. S sample standard deviation. The only difference between formula 1 and formula 2 is the 3 in formula 1.
