释义 |
Exponential DistributionGiven a Poisson Distribution with rate of change , the distribution of waiting times between successivechanges (with ) is
which is normalized since
This is the only Memoryless Random Distribution. Define the Meanwaiting time between successive changes as . Then
 | (4) |
The Moment-Generating Function is
so
The Skewness and Kurtosis are given by
The Mean and Variance can also be computed directly
 | (15) |
Use the integral
 | (16) |
to obtain
Now, to find
 | (18) |
use the integral
 | (19) |
giving
If a generalized exponential probability function is defined by
 | (23) |
then the Characteristic Function is
 | (24) |
and the Mean, Variance, Skewness, and Kurtosis are
See also Double Exponential Distribution References
Balakrishnan, N. and Basu, A. P. The Exponential Distribution: Theory, Methods, and Applications. New York: Gordon and Breach, 1996.Beyer, W. H. CRC Standard Mathematical Tables, 28th ed. Boca Raton, FL: CRC Press, pp. 534-535, 1987. Spiegel, M. R. Theory and Problems of Probability and Statistics. New York: McGraw-Hill, p. 119, 1992. |