The  Sixteen  Human  Error  Modes

The essence of Mistake-Proofing is to design both products and processes so that human errors or mistakes are impossible to make or, at the least, they are easy and early to detect and correct.

When performing a Mistake-Proofing analysis on a manufacturing, service, or business process, it is, of course, important to identify every human error possible during each process step.

The Human Work Model and the associated Sixteen Human Error Modes described in this article have been proven to be very helpful in identifying potential Human Errors when applied properly to every activity of any manufacturing, service, or business process.

Due to its simplicity and value, when applied properly, Mistake-Proofing has become one of the building blocks of most Lean Six Sigma and Operational Excellence initiatives.

The Sixteen Human Error ModesThe benefits of systematic Mistake-Proofing are:

  • the systematic analysis of a manufacturing, service, or business process,
  • the identification of critical and/or significant process characteristics,
  • the development of an effective control plan,
  • the identification of process deficiencies and development of an effective corrective action plan, and
  • the systematic documentation of the rationale for changes.

The Sixteen Human Error Modes

  1. Omission
  2. Excessive/insufficient repetition
  3. Wrong order
  4. Early/late execution
  5. Execution of restricted work
  6. Incorrect selection
  7. Incorrect counting
  8. Misrecognition
  9. Failing to sense danger
10. Incorrect holding
11. Incorrect positioning
12. Incorrect orientation
13. Incorrect motion
14. Improper holding
15. Inaccurate motion
16. Insufficient avoidance



A worker reads a work order sheet, selects an appropriate part, and assembles it onto a corresponding sub-assembly product.

Decomposition in Work Segments:

  I.   Reading the work order sheet

 II.   Getting a part to be assembled from parts boxes

III.  Assembling the part onto the sub-assembly product

Human Work Model & Error Modes: 

  I.   Reading the work order sheet parts boxes                                       

Forgetting to read the sheet (mode 1: omission)                                     

Reading the wrong sheet (mode 6: incorrect selection)                          

Misreading the sheet (mode 8: misrecognition)                                        

  II.  Getting a part to be assembled from  

        Forgetting to get the part (mode 1: omission)

        Selecting the wrong part (mode 6: incorrect selection)

        Dropping the part (mode 14: improper holding) 

III.  Assembling the part onto the sub-assembly product

Forgetting to assemble the part (mode 1: omission)

Assembling onto the wrong sub-assembly product (mode 6: incorrect selection)

Holding a damageable part of the sub-assembly product (mode 10: incorrect holding)

Assembling the part in the wrong position (mode 11: incorrect positioning)

Assembling the part the wrong way around (mode 12: incorrect orientation)

Inaccurately assembling the part (mode 15: inaccurate motion) 

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