- a chart on which observations are plotted as ordinates in the order in which they are obtained and on which control lines are constructed to indicate whether the population from which the observations are being drawn is remaining the same: used especially in industrial quality control.
- 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
