Exponentially smoothed control charts for the inverse-gaussian process

Exponential smoothing technique is used to obtain centrality and dispersion control charts for an Inverse-Gaussian(IG)process. The centrality and dispersion control charts use linear combinations of IG and chi-square random variables, respectively. Simulation results are used to verify the approximate distribution of the linear combinations. A method for choosing the “best” value for the weighting constant is presented. An example illustrates the computations that are involved in finding the control limits.