In recent years, the study of safety and risk assessments has become more important and is used in different fields of risk management. A model used to assess risk is the Swiss Cheese Model by James Reason. The model can be used to understand how negative outcomes occur and how to prevent them.  

It was originally developed for manufacturing companies like shipyards, oil industries and airline companies, but is now used by a wide range of companies to reduce negative outcome and create better systems by identifying weak points and develop procedures to address them.   

Swiss Cheese Model (Layers, Holes & Barriers/Defences)

The model explained 

Each slice of cheese represents a defense that the organization has taken against an error or risk to minimize an incident occurring. When all these slices are put together, it provides an overall picture of how the organization's defense against risk is in general.  

Each slice of cheese has randomly placed and sized holes representing flaws and weaknesses in systems that could potentially lead to undesired incidents occurring. Sometimes these wholes overlap each other and can go all the way through the row of slices. In this context, there are weak points that go through all areas within the organization and therefore have a high potential for the incident to occur. In theory, lapses and weaknesses in one defense do not allow a risk to materialize  since other defenses also exist  to prevent a single point of failure.   

One thing The Swiss cheese model often shows is how an error cannot be traced back to a single root cause, but that it often involves a combination of different factors including latent errors, which are errors that lies dormant in procedures and systems until it contributes to an accident. These often lead to active errors, which are directly connected to an accident and often made by employees in the organization. Which is why evaluations of procedures are necessary and part of this model.  

The advantage of using the model is that it can be used as a simple way to educate and present knowledge of risks the organization has to employees inside a complicated area. An important part of this is that just like other models and tools it’s not foolproof and can always use an extra layer. 

https://thedecisionlab.com/reference-guide/management/swiss-cheese-model

http://blog.enterprisetraining.com/swiss-cheese-accident-causation-model/