This application computes the ARL for Xbar, S and combined Xbar-S control charts for different mean and sigma shifts. It shows where to place the control limits for different in-control ARLs. In addition it plots the ARL curve for mean or sigma shifts. Moreover, it is possible to compare two sampling plans (sample size and frequency of sampling) in order to find the most efficient one to detect a process shift (smaller ATS). And it is possible to optimize the sample size for a given shift to minimize the ATS. There is a twin version for iOS / Iphone available in its store. Available languages are at the moment Spanish and English.