= How do I produce random variables which follow a negatively skewed distribution? =
Most distributions such as the exponential and log-Normal distributions are positively skewed with the mode of the distribution occurring for lower values.
The Weibull distribution is negatively skewed and may be generated [http://www.taygeta.com/random/weibull.xml using random variables which are uniform on the interval [0,1]]
The below produces an open ended negatively skewed weibull distribution with parameters, 2 and 20. It has a median of
$$2^text{-0.05}ln(2)^text{0.05}$$
= 0.95.
(See [http://www.weibull.com/AccelTestWeb/weibull_distribution.htm here for formulae).]
{{{
compute wrv= (-(1/2)*(ln(1-rv.uniform(0,1))))**(0.05).
exe.
}}}