Hi, I'm starting with SPC in my company. To my understanding to run SPC you need first to set up what I call the benchmarks (UCL and LCL) using a set of historical data. Once this defined you plot all new values against those and check for OOC results. My colleagues use to run statistical on the data and where looking also for OOC points. Doing like this you get moving UCL and LCL. They don't use historical data. What is correct practice ? Regards, Guy Please excuse my English, it is not my mother tong.