The result of seven measurements in a row on one side of the mean in a control chart is called “The Rule of Seven.” This is an assignable cause. 1 is incorrect because out of control means one measurement exceed the control limits. 2 is incorrect because in control means the result of one measurement stayed within the control limits. 4 is incorrect because the Rule of Seven doesn’t always signal quality improvement. It could, in some instances, signal that mean is set too low for the project.