Types of Checklists. Defensive Checklists and Negative Checklists

A Bit of History

In the spring of 2024, the blog’s theme inspired one of the internet users to write the own article about checklists. The article discusses an unusual type of checklist, which will be described further.

Under the article there was a discussion, and another user said that the “negative checklist” is the right term for the phenomena.

I disagree. In my opinion, these checklists are quite different, although both deserve attention. Let’s do the deeper dive.

Shouldn’t We Talk Here About the Read-Do Checklist and Do-Confirm Checklist?

Readers, especially those of this blog, may already be familiar with some types of checklists: action checklist (Read-Do checklists) and inspection checklist (Do-Confirm checklists). A separate post on the blog is dedicated to these two types, which we will not delve into now. This blog post is dedicated to the two different types, the ones you might have overlooked, but anyway completed intentionally.

We will also not address the question of what a checklist is in general. For that, there is another dedicated post, where you can find many links to additional materials. For example, there’s a post about the research on paper topic or an article on how to create checklists.

Today, we’ll talk about special types of checklists that are rarely mentioned yet frequently encountered in life.

Defensive Checklist and Examples

A Defensive checklist can be roughly defined as follows:

If a checklist is the road to a goal or a check to ensure we’ve reached the right destination, then a defensive checklist is the safeguard against losing the correct path. For instance, to travel to Australia, one must not buy tickets to Austria.

The ways to make mistakes are so numerous that they could easily outnumber the main checklist’s items. Therefore, it’s worth mentioning only those that pose a real threat when accomplishing the main repetitive tasks. Otherwise, you will receive the dramatically not effective checklist.

From the definition provided above, it is clear that a minus checklist is not entirely standalone. It needs a regular checklist to provide additional checks.

The BBQ Example

Let’s look at the basic example. This simple example describes a checklist accompanying barbecue preparation. The task is to follow the recipe and cook delicious barbecue. At the same time, there are things we must avoid doing as they would ruin the dish. The defensive checklist helps to protect against cooking mistakes here.

Here’s how a pork ribs BBQ recipe. In it, we are not relying solely on luck but also have different tasks full of protective measures:

☐ Take the Pork Ribs
  ☐ Avoid ribs that are overly fatty, have a grayish color, or smell off
  ☐ Look for ribs with a good amount of meat between and on top of the bones to ensure a satisfying barbecue
  ☐ Ensure you remove the silver membrane from the back of the ribs; this tough layer can ruin the texture
☐ Marinate the Ribs
  ☐ Rushing the process can result in bland-tasting ribs. Allow at least 4-6 hours or overnight for best flavor
  ☐ Excess salt can draw out too much moisture from the meat, making it dry and overly salty
  ☐ Avoid sugar-rich marinades too early as they can burn quickly on the grill, leading to a bitter, charred crust
☐ Grile the Ribs
  ☐ High heat can burn the outside before the ribs cook through. Stick to low and slow heat for tender meat
  ☐ Starting on a cold grill can cause uneven cooking and prevent a proper sear
  ☐ Too much sauce applied early can lead to flare-ups and burnt ribs. Save basting for the final 10-15 minutes

I asked ChatGPT to help me create a recipe with threats. If you feel there are significant problems with it, and it’s not a good checklist, please write in the comments so that we can fix it together.🙂

The “Checklist Manifesto” Example

A hidden list of protective minus checks can also be found in the famous book “Checklist” [1].

Here are the details of one of the sharpest checklists I’ve seen, a checklist for engine failure during flight in a single-engine Cessna airplane — the US Airways situation, only with a solo pilot. <...> But step one on the list is the most fascinating. It is simply: FLY THE AIRPLANE. Because pilots sometimes become so desperate trying to restart their engine, so crushed by the cognitive overload of thinking through what could have gone wrong, they forget this most basic task. FLY THE AIRPLANE. This isn’t rigidity. This is making sure everyone has their best shot at survival.

In a sense, “FLY THE AIRPLANE” can be understood as “Don’t stop flying the plane,” a defensive inclusion in the main checklist. It’s here so that a pilot fly the plane safely, the crucial activity among the current objectives of the pilot.

A Few More Comments on the Defensive Checklist

The BBQ example is clear enough, but that doesn’t mean this checklist type is limited to such situations. Safeguards against straying from the path can be applied everywhere — from simple recipes to complex, repetitive processes in big companies.

Also, one can notice that the defensive checklist here doesn’t have to keep the particular order. The main checklist here settles order of steps required to reach the goal.

Negative Checklist

Do you recall the difference between a blacklist and a whitelist? Intuitively, a blacklist feels like it’s about complete darkness, while a whitelist is as bright as daylight. However, if you create a blacklist on your phone, a few unlucky callers won’t be able to reach you. On the other hand, using a whitelist means only a few lucky individuals can contact you.

Similarly, although a negative checklist sounds intimidating, it offers more freedom than a conventional one. Let’s attempt to define it.

I can’t promise this definition won’t evolve, but let’s leave it as is for now. Let's see an example of how a negative checklist works.

The Negative Checklist From the Financial World

The example article [2] discusses Joel Tillinghast, a successful financial portfolio manager. His business processes are built around answering the question “where not to invest” to resolve “where to invest.”

First, undervalued stocks are identified based on several indicators, and then they are filtered out using a negative checklist. This provides efficient risk reduction and increases the quality of the purchased financial instruments.

Is There Really a Difference Between These Checklist Types?

Yes, there is a significant difference between a defensive checklist and a negative checklist. In the first case, the aim is to achieve a highly accurate result at best possible efficiency, with protective points documented along the way.

For the second case, the goal is to accept a broad range of outcomes. In culinary terms, the task is not to cook a specific barbecue but simply to eat something, as long as it’s neither spicy nor sour.

Both types of checklists have advantages and drawbacks. The first type documents and ensures high precision, providing a predictable process. This is often beneficial in business, where such checklists help achieve consistent results and maintain control. However, they may fail under changing circumstances. Would much remain relevant if pork ribs were substituted with potatoes?

The second type does not guarantee task precision, it doesn't even document it. Instead, it allows for flexibility, the freedom to choose how to achieve a goal, and the ability to add new points as needed. This is akin to a to-do list, particularly useful for creative work where some boundaries are still necessary.

Conclusion

Although the mentioned types of checklists initially seem very similar, these are quite different tools. Defensive checklists are auxiliary checklists for the regular ones, enhancing task accuracy. Negative checklists are the ones that provide ample room to solve broadly defined problems.

Pleased to learn how to enhance checklist with auxiliary defensive checklists? Subscribe to the “So List” blog and discover more about the forms lists and checklists take. You’ll be amazed at their variety!

References

[1] Atul Gawande “The Checklist Manifesto: How to Get Things Right”, ISBN 978-0312430009
[2] “The Negative Checklist: Reducing Errors” from the “Novel Investor” website