If Coefficient of SK=1, and co-efficient of kurtosis is = 4, then what is behavior of the
distribution?
Answers
Answer:
Kurtosis is a measure of the “tailedness” of the probability distribution. A standard normal distribution has kurtosis of 3 and is recognized as mesokurtic. An increased kurtosis (>3) can be visualized as a thin “bell” with a high peak whereas a decreased kurtosis corresponds to a broadening of the peak and “thickening” of the tails. Kurtosis >3 is recognized as leptokurtic and <3 as platykurtic (lepto=thin; platy=broad). There are four different formats of kurtosis, the simplest is the population kurtosis; the ratio between the fourth moment and the variance.
In EXCEL the “excess kurtosis” is calculated by the function KURT(array) which gives the population kurtosis minus 3 (kurtois-3). Therefore, in EXCEL zero indicates a perfect tailedness and positive values a leptokurtic distribution.
A detailed knowledge of skewness and kurtosis is rarely important in the laboratory but since the statistics are easily available they may serve as indicators of normality.