Contents
- Index
Johnson Family of Distributions
Shape:
The Johnson family of distributions is made up of three distributions: Johnson SU, Johnson SB and lognormal. It covers any specified average, standard deviation, skewness and kurtosis. Together they form a 4-parameter family of distributions that covers the entire skewness-kurtosis region other than the impossible region. The Johnson SU distribution covers the area above the lognormal curve and the Johnson SB covers the area below the normal curve.

Density Function - Johnson SU Distribution:
The density function of the Johnson SU distribution is shown below:

The equation, parameters and bounds of the density function are:

Moments - Johnson SU Distribution:
The moments of the Johnson SU distribution can be calculated from the parameters as shown below:

Density Function - Johnson SB Distribution:
The density function of the Johnson SB distribution is shown below:

The equation, parameters and bounds of the density function are:

Moments - Johnson SB Distribution:
The moments of the Johnson SB distribution do not have a simple expression.