Causal Patterns and Five Examples

Humans are great at finding meaning in a wide and diverse array of data.  This is, in part, because we are very good at recognizing patterns.  At first, a new experience can be overwhelming.  Think about it from the perspective of a newborn baby (if you can).  It’s no wonder they cry so much given the enormity of their experience!  But over time, they find consistencies and patterns that make cognitive overload less overwhelming, more predictable, and manageable.

Those of us that do root cause analysis for a living also identify patterns that make our jobs easier, albeit with marginally less screaming and crying.  Although we teach cause and effect analysis as being a process of deconstructing effects into their individual causes, that’s not always how we do it professionally.  We often find that we’ve been down a certain path before.  One of the benefits of building a cause and effect logic diagram is that it allows us to spool up similar past experiences in the form of generic “causal patterns.”  These causal patterns are defined at a higher level of abstraction.  They are not specific, but they provide the investigator with a starting point that can help speed up the root cause analysis while enhancing quality.  So we thought it would be useful to publish some of our favorites.  This list is by no means exhaustive.  But it should be useful in a variety of applications, and will demonstrate the utility of cause patterns in general.

Spills

A spill can be defined as any form of primary containment loss.  Examples include a cup of milk spilled by a toddler or a 50,000 gallon release of ammonia.

Most spills are caused by:

1.  Spill Initiated:  Upset container, opened valve, punctured container, or any other similar sort of initiating event.  Note that there are some implied conditions.  For instance, upsetting the container means that the container was sufficiently tipped to such a degree to allow the substance to overtop the edge of the container.  A puncture will only result in a spill if it occurs below the level of substance in the container.  The same is true with an opened valve – the inflow to the valve must be below the substance level.  If required, these could be “decompressed” to show the more granular detail.  Spill initiation can be a form of exceedance, described below.  For instance when a cup tips to a certain angle before the liquid inside spills out.  It can also be the result of impact, such as when a cup is impacted with sufficient force to upset the cup. 

2.  Substance in Container:  In order to spill something, whatever it is must be present in the container.

3.  Exit point in container:  There must be a pathway from which the contents exit the container.

Damage

1. Contact:  Most forms of damage involve contact of some sort.  Two cars hitting each other, a glass striking the ground, or a falling object hitting someone in the head – all are forms of contact.
2. Sufficient force:  Contact alone is not enough – you also need a sufficient amount of force in order to cause damage.  For instance, a rain drop can fall for a thousands of feet from a cloud overhead, but do no damage when it hits you.  A golf ball-sized hailstone, on the other hand, may knock you to the ground.  The difference is the amount of force associated with the contact.

Exceedance

1. Expected result:  This can be a scheduled meeting start time, a mill specification, a preventive maintenance due date, a desired weight, a deadline, a desired delivery date, etc.
2. Actual value:  This is the actual value, such as actual meeting start time, actual part dimension, when the preventive maintenance activity was performed, the actual weight, the actual delivery date, etc.

Fire (at Ignition)

1. Ignition source:  A match strike, contact with an existing heat source, a static spark (completed circuit -described above) are all types of ignition.
2. Combustible material:  That’s what burns.  Well, as was explained to me recently during a fire investigation, gasses that are produced by heat are what actually burn, but you get the idea.
3. Oxygen:  Most fires require a source of oxygen.  Often this is just the atmosphere, but if a fire occurs in an environment that is supposed to be inert, this pathway becomes very valuable.

Human Error

1. Person took action:  The possibilities are endless, but let’s say they initiated forklift activity to move a pallet of product from the production area to the finished goods area.
2. Plan was Faulty:  People take action for a reason, such as to move product that has been completed from the production area to the finished goods area.  But if their plan omitted checking with the operators in charge of production prior to moving product, then there was a gap in the plan.  They may have successfully executed the move – but the result was not what they intended.
   AND/OR
3. Execution was Faulty:  Same example as above, but this time the product was complete and ready to be moved, but the forklift driver ran into a wall and destroyed all the finished goods on the pallet.  Oops.  In this case, the plan was fine – but the execution broke down. 

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