INTRODUCTION
The log-normal distribution is widely used in many areas, such as environmental
study, survival analysis, biostatistics and other statistical fields. It is a right skewed
distribution with a long tail. Figure 1 displays the log-normal density curves with
different parameters. The log-normal distribution has a close association with the
normal distribution. By taking the natural logarithm of a random variable, the
random variable then will have a normal distribution.