When a worker calls in sick, a temporary replacement is hired to operate his machine. During the week in which the replacement is working, scrap increases significantly, to the point that almost all points plotted on the control chart used to monitor the machine, fall well above the central tendency. Management is frustrated because it cannot understand why the process has deteriorated so rapidly. However, when the original worker returns, scrap decreases to the original level. Management is satisfied it has fixed the problem somehow once and for all although it doesn’t have any idea how the high rate of scrap occurred. According to Deming, this is an example of management: I incorrectly identifying common cause variation present as special cause variation. II under controlling the process by not reacting to special cause variation occurring. III correctly identifying special cause variation. IV correctly identifying common cause.