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Global 8D – D4: Define and Verify Root Cause and Escape Point

Posted by Graham Cripps on Tue, Aug 04, 2015 @ 09:30 AM

G8D Root Cause

Global 8D – D4: Define and Verify Root Cause and Escape Point

Graham Cripps, Director


At this stage in the G8D problem solving process you have now established the Interim Containment Action (ICA) thus buying some valuable time to concentrate on solving the problem permanently. Also you will have reviewed the team composition to include all the right skills and experience are available for the next step in the problem solving effort.


 Download your FREE Root Cause Worksheets

Before I go any further I need to establish two key definitions: -

Escape Point: - the place in the process where the root cause of the problem went undetected allowing the problem to occur

Root Cause: - the lowest level event that can be attributed and proven as that which caused the problem to occur

The Global 8D process uses a number of forms to help drive this process and are as follows: -

  • Differences and changes worksheet

  • Possible causes worksheet

  • Possible root causes worksheet

These sheets are used to drive the discussions and problem solving efforts and form part of the process for narrowing down causal theories to the root cause.


G8D Process Outputs

As already mentioned, the G8D process is structured in a way that drives down from the effect or symptom, to the problem and then the root cause. Like a funnel, the process is about filtering out all the theories and ideas using facts (data driven) to be able to find and verify the root cause.

The object of all problem solving is to get to root cause and then take action to correct and sustain the improvement.




Define Root Cause

To explain the process I will use sections of the worksheets to aid understanding and to demonstrate how these worksheets are used.

STEP 1 – Define what is different about the 'IS' compared to the 'IS NOT'

G8D   Worksheet Alignment 1

For this step we use the differences and changes worksheet to help drive the process.

This model shows the Is/Is Not worksheet and the Differences and Changes Worksheet side by side.

You will notice that the Is/Is Not and the Differences and Changes worksheets align.

The reason for this is that the question is asked for each entry on the Is/Is Not form “what is different in, on or around the “IS” when compared with the “IS NOT”?



Fundamentally there must be differences between the 'IS' and the 'IS NOT' or both would have the problem

Then we need to ask the question what has changed in, on or around the 'IS'? Something must have changed or the problem would have always been there. This must be factual so it’s OK to generate a question log or ask a team member to go and find out.  

STEP 2 – Develop Possible Causal Theories

G8D   Possible Causes

The Possible Root Causes Worksheet is used to record each root cause theory.

First brainstorm the possible causes and record on a separate media.

For each of the causes develop a causal theory that explains how that possible cause would result in the problem being experienced.

Example: the problem could be that the car would not start and the possible cause is 'the auxiliary belt is slipping'. The developed causal theory might read 'the auxiliary belt has worn and is now slipping causing the slow rotation of the alternator thus delivering reduced charge for the battery. The battery has therefore lost charge over time'.

A causal theory is developed for each possible cause.

STEP 3 – Establish Possible Root Causes

G8D   Possible Root Causes

Using the Possible Root Causes Worksheet (which is again aligned to the 'Is/Is Not' worksheet), ask for each causal theory the question for each entry on the 'Is/Is Not' worksheet, does this explain the reason why the problem exists on the 'IS' and not on the 'IS NOT'

For each time the answer is yes put a plus (+) sign. If you do not know or need to find out put a question mark (?). If the answer is no, put a minus sign (-)

When a no is established then this possible cause cannot be a possible root cause. Move onto the next causal theory. Complete this for all causal theories. The results you will be left with are all of the possible route causes.

This is a complex step in the problem solving process and needs diligence on the part of the G8D Team members to ensure assumptions are not made. If in doubt, go and find out!

STEP 4 – Verify Possible Root Causes

For each of the possible root causes, there now needs to be a practical activity to verify the possible root cause. This should be carried out in practical terms where ever possible. However, in some instances modelling may be required.

If the possible root cause is introduced then this should 'switch the problem on'. Once the possible root cause has been removed, this should 'switch the problem off'

This process is repeated for both the root cause of the problem and the root cause for the escape point.

Complete the G8D Form (Template)

G8D Report


Complete the Global 8D form and circulate. Remember to update team composition for any changes that are made at the end of this stage.

The G8D form is a summary of the problem solving activity and is suppoirted by all of the other worksheets, data and supporting information (including the worksheets above) that is generated as a result of the Global 8D problem solving activity.




Graham Cripps

Resuts Consortium Ltd

 Download your free Is-Is Not template  Download Your Global 8D Report Template



Topics: Root Cause, root cause analysis, Global 8D, G8D, Interim Containment Action, Escape Point

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