control chart
n (Statistics) statistics a chart on which observed values of a variable are plotted, usually against the expected value of the variable and its allowable deviation, so that excessive variations in the quality, quantity, etc, of the variable can be detected
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014