Not All Customer Experience Variation is Equal: Common Cause vs. Special Cause Variation

Variability in customer experience scores is common and normal.  Be it a survey of customers, mystery shops, social listening or other customer experience measurement, a certain amount of random variation in the data is normal.  As a result, managers need a means of interpreting any variation in their customer experience measurement to evaluate if the customer experience is truly changing, or if the variation they are seeing is simply random.

In a previous post, we proposed the use of control charts as a tool to track customer experience measurements within upper and lower quality control limits, giving managers a meaningful way to determine if any variation in their customer experience measurement reflects an actual change in the experience as opposed to random variation or chance.

Now, managers need to understand the causes of variation, specifically common and special cause variation.  Common and special cause variation are six sigma concepts, while most commonly used in industrial production, they can be borrowed and employed to the customer experience.

Common Cause Variation:  Much like variation in the roll of dice, common cause variation is natural variation within any system.  Common cause variation is any variation constantly active within a system, and represents statistical “noise” within the system.

Examples of common cause variation in the customer experience are:

  • Poorly defined, poorly designed, inappropriate policies or procedures
  • Poor design or maintenance of computer systems
  • Inappropriate hiring practices
  • Insufficient training
  • Measurement error

Special Cause Variation: Unlike the roll of the dice, special cause variation is not probabilistically predictable within the system, as a result it does not represent statistical “noise” within the system, but is the signal within the system.

Examples of special cause variation include:

  • High demand/ high traffic
  • Poor adjustment of equipment
  • Just having a bad day

When measuring the customer experience it is helpful to consider everything within the context of the company-customer interface.  Every time a sales or service interaction within this interface occurs the customer learns something from the experience and adjusts their behavior as a result of the experience.  Managing the customer experience is the practice of managing what the customers learn from the experience and thus managing their behavior in profitable ways.

A key to managing customer behaviors is understanding common cause and special cause variation and their implications.  Common cause variation is variation built into the system: policies, procedures, equipment, hiring practices, and training.  Special cause variation is more or less how the human element and the system interact.

See earlier post:

Not All Customer Experience Variation is Equal: Use Control Charts to Identify Actual Changes in the Customer Experience

 

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About Eric Larse

Eric Larse is co-founder of Seattle-based Kinesis CEM, LLC, which helps clients plan and execute their customer experience strategies through the intelligent use of customer satisfaction surveys and mystery shopping, linked with training and incentive programs. Visit Kinesis at: www.kinesis-cem.com

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