What is the Swiss cheese model?

• A. A method for mathematical risk scoring
• B. A model illustrating how multiple layers of defense can prevent errors, with holes that align to cause harm
• C. A diagram for time management
• D. A budgeting framework

Answer: (B)

In patient safety and systems thinking, the Swiss cheese model shows how several layers of protection work together to prevent errors, but each layer has its own weaknesses. Each slice of cheese represents a defense—things like protocols, double checks, alarms, training, and independent verification. The holes in each slice are the gaps, latent conditions, or points where a defense might fail. An adverse event happens when the holes line up across multiple layers, creating a path for an error to reach the patient. This concept emphasizes that risks aren’t eliminated by a single safeguard; instead, safety comes from multiple independent defenses whose weaknesses don’t coincide all at once.

That’s why the model is the best answer: it captures the idea that layering defenses reduces risk, but gaps can align to cause harm if not addressed, guiding how to strengthen systems with redundancy and better processes.

It isn’t a method for mathematical risk scoring, a diagram for time management, or a budgeting framework, which is why those options don’t fit this concept.