Job Hazard Analysis - I2P2

Job Hazard Analysis – Generic Error Model System

March 25, 2011 · 0 comments

in Job Hazard Analysis

We came across the Generic Error Model System in the U.S. Department of Energy’s Standard on Human Performance Improvement Handbook published in June 2009. On review of the Generic Error Model System concept as presented in the DOE Handbook, we believe that identification of the type of performance should be incorporated into the review of a job and into the fundamentals of the job hazard analysis process.


The GEMS model is based on the work of

Reason and Rasmussen. It was designed to show how humans make use of information and how performance must move between various levels of attention. For each task, performance requirements may change as each step of the task is completed. Some tasks can stay at the same level with minimal thought required. Higher involvement is necessary as decisions must be made or problems resolved.

As a task is completed, it requires either one or a combination of skill based performance, rule based performance, and or knowledge base performance. Each of these place different requirements on the working memory and skill sets needed by the individual or individuals completing the tasks.

Performance Types

Skill based performance can be automatic and according to the handbook, reduces the load on working memory by approximately 90%. Skill-based performance is largely found in jobs with physical actions that are completed in very familiar situations. Most of the actions of skill based tasks can be completed from memory without significant conscious thought.

Rule base performance requires the use of memorized or written rules. These may be acquired through formal training or by working with experienced personnel or from use of standard operating procedures or structured actions. Rule based performance follows an “If, Then” process. In other words, if the performer of the task identifies a situation that is not in the parameters of the job, he or she makes a decision based on predetermined actions or rules. If “X” happens, then I must do “Y”. Examples from the DOE Handbook include deciding when to replace a ball-bearing has been inspected; responding to an alarm; executing or using emergency operating procedures. A decision has to be made by the individual and that decision is based on training, rules, guidelines or actions that have been pre-determined.

Knowledge base performance requires a response to unfamiliar situations where specific rules or actions have not been predetermined or may not apply given the situation. Knowledge base situations are those that are considered unusual and require troubleshooting, conducting analysis, conducting experiments. They require the use of problem solving and analytical skills.


Currently, most job hazard analyses do not include a review of the types of performance decisions that have to be made by the person completing the task. We assume that a person can simply move from step to step using the same performance skills, mindlessly implementing the controls as determined by the Job Hazard Analysis.

This is probably because the use of job hazard analysis began during early industrial work where most of the jobs being analyzed were of the skill-based performance as found on assembly lines or basic manual work and did not require rule-based or knowledge-based performance.


We recommend that as part of your ongoing job hazard analysis process, that you incorporate or at least review whether or not the job requires a variety of performance types. Any of the three types may be required at different times during a job’s completion. If so, then training may need to include more depth of expertise in problem solving. Standard Operating Procedures, guidelines and communications may also need to be modified based on the performance types if risks and hazards are to be kept under control.


US Department of Energy Human Performance Improvement Handbook, Volume 1, DOE-HDBK-1028-2009
Roughton, James, Nathan Crutchfield; Job Hazard Analysis. A Guide to Compliance and Beyond, Butterworth-Heinemann, 2008

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