Control chart alarms when no variation in data
I have a script where we generate control charts for a lot of parameters. For some parameters there is no variation in the data (e.g. all data are below detection limit). For these parameters with no variation all samples show warnings, e.g. Test 1 (One point beyond Zone A). These warnings/alarms don't make sense in our situation. Is there a trick such that I can avoid warnings when there is no va...