Your ST-PRA Guide To Producing Better Outcomes


The name is quite a mouthful and a powerful way to find the likely risks and errors of your staff within the systems and environment they work in.

At Outcome Engenuity, we have pioneered the development of Socio-Technical Probabilistic Risk Assessment (ST-PRA). From our early work with the National Aeronautics and Space Administration (NASA) to several aviation companies, railroads, and healthcare institutions, we are renowned for bringing state-of-the-art modeling into highly sophisticated, technical environments.
Begin your discovery of what ST-PRA will reveal for you  – we’ll build the risk model, develop, test, and implement interventions, and measure their success.

Probabilistic risk assessment has been a useful tool in analyzing the risks in high-consequence fields such as aviation for decades. We’ve taken a tool that is primarily used in engineering and evolved it into something better – something that helps us examine the human elements in a process.

What makes ST-PRA an evolutionary step is that the entire risk model is made up of human errors and at-risk behaviors – attempting to model the as-is state of a predominantly human process. Where traditional PRA will generally model a technical system with some input of human errors, the ST-PRA attempts to model human errors and human variations – where one task may be performed many different ways within one risk model.

Healthcare in general can be complex, with risks that vary from equipment failure to human error or at-risk behavior to patient administration errors. Risks within healthcare have long been managed on an event-by-event basis. Building a socio-technical risk model allows healthcare to see risks in a manner previously unavailable. Even for those organizations that have collected event data, this data does not provide any visualization of the interconnectedness of choices and errors that might combine to lead to a medical error. Additionally, many quality assurance systems today do not account for the presence of behavioral norms that are part of the socio-technical model. Building a top-level event fault tree will allow hospitals and healthcare systems to have a much more inclusive model of risk.

ST-PRA is still growing. The unique techniques and rules required to effectively model human behavioral risks within a fault tree are still advancing. Given, however, that human errors and behaviors are major contributing factors to most accidents in high-consequence industries, this is a development effort that must continue – despite the uncertainties in the socio-technical aspects of risk modeling.

Let’s look at aviation to help explain the origins of ST-PRA. Taking a historical view, probabilistic risk assessment (PRA) has an extensive application in strictly mechanical systems, where engineering objects (devices, vehicles, systems, subsystems) have been structurally analyzed for risk possibilities using a variety of tools (e.g., fault trees, failure modes and effects analysis, hazards analysis). This approach has been particularly successful in providing design guidance. However, we know that these same objects are placed and used in operational environments in which many other risks can affect the risk of failure. For example, weather (such as a sea air environment) may significantly accelerate corrosion properties of an aircraft. Humans who work with mechanical objects may significantly accelerate the chance of failure due to mere handling or testing of systems as well as collateral damage due to human error.

In recent years, the PRA of mechanical systems has been augmented with some incorporation of human error models (e.g., organizational factors, ergonomic considerations), which included performance shaping factors. This enhancement has been difficult and slow primarily because of the lack of human error data precise enough for design engineers. Additionally, because operator environments and operator use of equipment will vary between operators, it is also difficult for the design engineer to model operational risk. In contrast to PRA of mechanical systems with some limited modeling of human errors, socio-technical probabilistic risk assessment (ST-PRA) is the PRA of socio-technical systems with limited modeling of equipment failure. It is a structured process for building a risk model from probability estimates of individual human errors and at-risk behaviors.

If you ‘re interested in ST-PRA for your facility or organization, please call us or inquire here for additional details.

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