Hi, When we plot review effectiveness (%) in control chart, the UCL is going beyond 100 and LCL is going below 0. However, this is not possible based on the formula of review effectiveness: Review effectiveness (%) = (Number of defects detected in reviews at a given stage) / (Sum of defect injected in that stage + number of defects slipped from earlier stages). Please suggest on whether we can force fit the UCL and LCL to 100 and 0. If we do this, how can we perform trend analysis for 3 different durations. Should we look at shift in mean, stdev etc. Best Regards, Bharani Kumar 9849312304