The Swiss Cheese Model helps explain why, despite all our best intentions, accidents happen.

Analysis of accidents in large complex systems such as power stations or plane crashes led to an understanding that "no one failure, human or technical, is sufficient to cause an accident. Rather, it involves the unlikely and often unforeseeable conjunction of several contributing factors arising from different levels of the system."

James Reason's Swiss Cheese Model is a memorable visual metaphor that illustrates how each safeguard may contain a latent flaw or hole and that an unfortunate circumstance may result in these holes lining up to disastrous effect. It's also a nice reminder that multiple layers of defence will be more effective, but even with our best efforts, there's still potential for something to go wrong.

Excerpt from Revisiting the "Swiss Cheese" Model of Accidents (pdf), Reason, Hollnagel and Paries, 2006.

Coronavirus example from the Cleveland Clinic.

I learned recently that it's sometimes called the "cumulative act effect".

This sketch, updated and polished, features with a number of others in my book Big Ideas Little Pictures.

The Swiss Cheese Model

A cheeseboard is a highlight of the holidays for me. Here are some simple guidelines on how to create a winning one that looks and tastes the part.

I think the key really is the range of textures in the cheese. If you’ve got a hard, semi-hard, and soft cheese you’re onto a good start. If you can add in a crumbly and creamy and make sure you have a range of strengths from mild to mature, stinky or blue you’re onto a winner. Then make it amazing by adding complements from the sweet and salty buckets and don’t forget the crackers and breads.

If you want show off, try to cover a range of cheese shapes, colours and milks such as goats and sheep as well.

And because you may find yourself curious about it: origins of Boxing Day

Compose a cheeseboard

Sacré bleu! Don't cut the nose off brie. Or camembert cheese, for that matter. Share the ripe middle by cutting strips.

Don’t cut the nose off brie

Turns out a bunch of substances have the power to make you sleepy - tryptophan, vitamin B6, calcium, glycine, lactucarium and carbohydrates are some of the major ones. Some even interact with each other for maximum sleepiness. A few common foods with these compounds in good measure include:

turkey, walnuts - tryptophan
tuna, pistachios - vitamin B6
dairy - calcium
chamomile - glycine
lettuce - lactucarium

So an evening turkey or tuna, walnut, cheese and lettuce sandwich with a glass of milk and a side of pistachios or walnuts and you’ll be set for a good night.

Cheese sketches