Specific Error Analysis Technique (SHERPA)

An error analysis allows you to identify potential hindrances that could occur during a task through a process known as human error identificaiton (HEI). HEI operates under the assumption that identifying the potential errors related to a task allow for measures or interventions to be implemented that will prevent those same errors in future iterations of a system or task. The specific erorr analysis technique (SHERPA) is a taxonomy-based HEI method that assigns specific taxonomic modes (action, retrieval, check, selection, and information communication errors) to errors associated with a specific step on a hierarchical task analysis (HTA). For each error, the researcher describes the error in detail, what consequences result from the error occurring, how likely that the associated step could be recovered at a later point in the task, probability of the error occurring, and a rating of criticality. For the final step, potential ways to diminish the likelihod of the error occurring are recommended.

An example of the specific error analysis technique (SHERPA) is shown below.

Example

Research Questions: What are the steps involved in sparring with someone using Krav Maga in a training setting? What are potential errors that coincide with each step? What are the consequences of those errors and the likelihood they may occur? How can they be prevented in future sparring sessions?

The first step in using the SHERPA method is to have a hierarchical task analysis (HTA) created. This helps to break down your task into its constituent parts so that you are able to properly identify points in which specific errors may occur. In this instance, I pulled from my own experience with Krav Maga to create the HTA, as well as spoke to a subject matter expert (SME; an authority on a specific topic - in this instance, my Krav instructor) from my gym who has more experience with sparring than I do. SMEs can be valuable sources of information and can aid you in better breaking down your task and identifying where errors may occur. The preliminary HTA can be seen below.

The next step in the SHERPA method involved assigning classifications to steps in the HTA. These classifications are as follows:

• Action - physical movements; in the context of Krav this would be things such as donning gear or throwing a kick

• Retrieval - getting information from an external source; in this example, one sparring partner is reading their partner's movement and body language to ascertain how to respond

• Checking - conducting a procedural check; this would align with ensuring that all gear is accounted for and properly donned

• Selection - choosing one alternative over another; during sparring, this would be choosing whether to attack or defend

• Information Communication - talking to another person; when sparring it is important to communicate with your opponent if you are injured after taking a hit, however this could also refer to post-match advice exchanged between fighters

More than one classification can be assigned to one overall step, however it is beneficial if substeps receive only one classification.

The actual error and their description then follow, however in some cases you may have already included them in your HTA. If this is the case, you need to ensure that the errors you have listed correctly associate with your chosen taxonomy and the step itself. After this was done for the sparring error analysis, I determined what the consequences of each error would be and included a brief description. In some cases, you may want to include more minute detail depending on your research questions and goals.

Recovery analysis refers to the likelihood of recovering from an error in a later step. This was interesting for this sparring example due to the cyclical nature of steps 3-5. During a sparring bout, you consistently return to fighting stance and the movement and assessment phases before performing an attack or defense. Because of this, errors in these phases have higher chances of being recovered, but they also have higher chances of occurring as well.

Ordinal probability analysis and criticality analysis are both rated on a scale of low, medium, and high. The former is an indicator how often the error occurs while the latter determines the likelihood of an error leading to a critical incident.

The final stage in the error analysis is recommendations for error reduction strategies, or the remedy analysis stage. Recommendations usually fall under four categories:

• Equipment - addition of a supplemental device or redesign of current technology in use

• Training - changes in training that would lead to reduced errors

• Procedures - implementation of new procedures or modification of exisiting ones

• Organizational - policy or culture changes

The final, completed error analysis for Krav Maga sparring can be seen below.

Things to Remember:

• With the SHERPA method your error analysis is directly linked to, and dependent on, the hierarchical task analysis that you create. Therefore it is important that your HTA contain all the requisite steps and details needed to make each assessment.

• Subject matter experts and other sources (such as research articles, creditable tutorials, etc.) can be used to inform both the HTA and error analysis

Pros:

• Easy to use and requires little training or instruction

• Provides an organized way to identify and analyze errors

• Most commonly used HEI method and has seen a lot of success in various domains

Cons:

• Very extensive HTAs can lead to the SHERPA method becoming long and tedious

• Cognitive components are not initially considered

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.

• Stanton, N. A., & Stevenage, S. V. (1998). Learning to predict human error: Issues of acceptability, reliability and validity. Ergonomics, 41(11), 1737–1756. https://doi.org/10.1080/001401398186162