What is an error?
Human error is defined as 'All occasions in which a planned sequence of mental or physical activities fails to achieve its intended outcome, and when these failures cannot be attributed to the intervention of some chance agency'
How are errors identified
An error analysis is a component of a larger task analysis which identifies such things as the frequency and type of error that can occur during a step within the overall task; this process is more generally known as human error identification (HEI). An error analysis allows designers, researchers, etc. to predict human or design errors that may occur.
The most common method of HEI is the Specific Error Analysis Technique (SHERPA) which consists of 8 steps.
Hierarchical Task Analysis (HTA) - this step is used to describe the task and break it down to its' constituent parts so that potential errors at each step can be identified
Task Classification - each bottom level task step in the HTA is assigned one of the following as a classification:
Action
Retrieval
Checking
Selection
Information Communication
Human Error Identification (HEI) - here is where the actual error, and description of that error, is listed.
Consequence Analysis - in this step, the consequences associated with each error are identified and defined
Recovery Analysis - recovery potential of an error is identified here; this refers to how likely it is that this step can be recovered at a later task
Ordinal Probability Analysis - the probability of the error is rated here using an ordinal probability scale of low, medium, high
Criticality Analysis - this step involves the analysis of the criticality of the error in question, meaning how likely it is that the consequence of the error would be severe. This is also rated using low, medium, and high.
Remedy Analysis - the final step involves suggesting error reduction strategies for that particular step
References
Embrey, D. (1986) SHERPA: a systematic human error reduction and prediction approach. International Topical Meeting on Advances in Human Factors in Nuclear Power System, pp. 184-193.
Bligård, L.O., & Osvalder, A.L. (2014). Predictive use error analysis – development of AEA, sherpa and phea to better predict, identify and present use errors. International Journal of Industrial Ergonomics, 44(1), 153–170. https://doi.org/10.1016/j.ergon.2013.11.006