Least Squares Quadratic (LSQ) Approximation to Lognormal Sum Distributions

In this paper, least squares (LS) approximation approach is used to solve the approximation problem of a sum of lognormal random variables. It is shown that least squares quadratic (LSQ) approximation exhibits an excellent match with the simulation results in a wide range of the distributions of the summands. Using the coefficients obtained from the LSQ method, closed-form expressions for the cumulative distribution function (CDF) and the probability density function (pdf) for the sum random variable and its logarithm, are presented