Understanding the Difference Between Process Complexity Versus Process Capability

Understanding the Difference Between Process Complexity Versus Process Capability
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A process is a sustained series of events or actions that effects change through a series of stages. It resembles an interactive algorithm where elements such as people, machinery, methods, materials, and measurements interplay with environmental variables such as “time” and “space” and reorganize or rearrange entities such as activities, products, decisions or contexts.

Process complexity and process capability are two major process related analysis. When comparing process complexity versus process capability, the two are interrelated and one very often influences the other.

Process Complexity

Process complexity is in simple terms, an assessment of the tasks or events that make up the process and through which a product, activity, or decision flows before reaching the output stage.

All business processes start in a simple conundrum of the input subject to transformation leading to output. As the business develops, this basic process becomes complex with the interplay of various elements and factors. Process complexity is a measure of the process difficulties that impede project execution.

The four basic factors on which process complexity rests include:

  • Granularity and coverage of activities, such as the type of activity and the nature of the product
  • Contextual interactions
  • Abstraction or process specificity
  • Modularization or sub processes involved in process execution

Failure to control these factors leads to increase in process complexity over time.

One popular way to gain an understanding of process complexity is through the fishbone diagram. This diagram lists out factors such as materials, machinery used, environmental factors, and others that influence the selected process characteristic and contribute to the complexity of the process. The diagram starts with general factors and delves into specific factors with the addition of each level or layer.

Process Capability

Process capability is the scientific measurement of a process output based on the extent to which the process output complies with the given specification limits, or capability indices, which in turn, reflects the set design parameters or customer demands.

Process capability finds expression as the ratio of the natural variability of a stable process with process specification limits. The more the natural variability measurements falls within the process specification limits, the more capable the process.

Measurement of process capability involves using control charts that aid detection and subsequent elimination of unnatural causes of variation, to achieve a state of statistical control or measurements falling within process specification limits.

The Interplay

When comparing process complexity versus process capability, the two remain interrelated.

The extent to which processes remain capable, that is fall within the defined statistical limit, depends on the extent to which project managers can control variability. Process complexity is a significant factor in the process remaining within the set limits, without the variability exceeding such limits. Simple processes are easy to control and manage. When processes become more complex, it becomes more error-prone, more difficult to understand, more difficult to maintain, and liable for frequent shutdowns.

Understanding process complexity allows predicting process capability, or the extent or number of times the process fulfills customer requirements. Improving process capability, or bringing the process under statistical control in turn, requires making fundamental changes to the process, making it less complex, easier to understand and control by removing the sources of variability.

One popular manifestation of the synthesis of process complexity and process capability is Lean Six Sigma. Lean approaches process complexity by eliminating waste and streamlining the process and the Six Sigma Methodology ensures the process attains statistical compliance, ensuring process capability.


  1. Howard, Newton; Rolland, Colette, and Qusaibaty, Ammar. “Process Complexity. Towards a Theory of Intent-oriented process deisgn.” Retrieved from https://cogprints.org/4877/1/aq_infos04_paper.pdf on April 09, 2011.
  2. Muketha, G.M. et. Al. “A Survey of Business Process Complexity Metrics.” Retrieved from https://www.scialert.net/abstract/?doi=itj.2010.1336.1344 on April 09, 2011.
  3. Symphony technologies. “Measuring Your Process Capability.” Retrieved from https://www.symphonytech.com/articles/pdfs/processcapability.pdf on April 09, 2011.
  4. Engineering Statistics Handbook. “What is Process Capability?” Retrieved from https://www.itl.nist.gov/div898/handbook/pmc/section1/pmc16.htm on April 09, 2011.

Image Credit: geograph.org.uk/Paul Johnston-Knight