Question

How is a control chart used? State six indications that a process is going out of control.

Short answer

Control charts are used as indicators whether the values being monitored are unnaturally far from the values being targeted. It uses the confidence intervals for a Gaussian distribution as its visual representation.

Step-by-step solution

Definition of control chart

A Control Chart is a visual representation of the confidence intervals for a Gaussian distribution.

The control chart notifies us when a property being examined strays dangerously far from an anticipated target value.

Six signs that a process might be getting out of control

Six signs that a process might be getting out of control are:

1. Keen observation outside the action lines.

2. There is always 2 out of 3 measurements between action and warning lines.

3. There are all 7 consecutive measurements above or below the centre line.

4. There are all 6 measurements which can be increasing or decreasing where they are located.

5. There are 14 points which are alternating up and down regardless where they are located.

6. A nonrandom pattern.