One note - for the Deming folks using SPC, you can set SMART goals, and not specify a numerical target.
If your process is stable, and operating at a level that is acceptable, the business goal becomes "Continue the process, with no statistically significant non-improving trends".
If your process is stable, and operating at a level that is not acceptable, the business goal becomes "Change the process, and achieve a statistically significant trend in the improving direction."
Then, all you need to do is specifiy which is the "improving direction", and the list of criteria for a statistically significant trend.
See attached presentation.