Many people are familiar with the concept of root cause analysis and the idea of digging down to identify the root of a problem, but one question that we get asked over and over is how deep should the investigation go? How many “why” questions are enough? What exactly does a thorough investigation look like?
The short answer is “it depends”, which admittedly is not particularly helpful to somebody trying to learn how to investigation issues. Unfortunately, there isn’t a simple, one-size-fits-all rule. How far you take an investigation depends on the magnitude of the issue and how much you want to reduce the overall risk of reoccurrence.
A general rule of thumb is that organizations will want to spend more time and resources investigating a big problem than a small one. While that makes sense intuitively, it doesn’t really answer the question of how to tell when an investigation is “done”.
One sign that you may be stopping an investigation too early is If you find yourself identifying the cause as something along the lines of “human error” or “procedure not followed”. It is important to ask a few more questions and dig a little deeper to understand exactly why the error was made or the procedure wasn’t followed. Understanding the details is important so that specific, detailed solutions can be developed and implemented. You can view recordings of our free webinars “How to Investigate ‘Procedure Not Followed’ – Introduction” and “Human Error, Human Performance and Human Factors” if you would like to learn more about this topic.
In addition, one of the best ways I have found for getting a sense for how far an investigation should be taken has been to read as many investigation reports as I can. If you have access to your organization’s previous investigation reports, you should definitely take advantage of that resource. (Also, pay attention! If you see a pattern of similar incidents popping up again and again, you’ve likely found examples of investigations that haven’t been taken far enough.)
Don’t despair if don’t have access to past investigations from your specific organization. There are many government agencies that publish reports of their investigations and these can be a great free resource for learning more about the types of questions that can/should be asked during an investigation. The websites for the U.S. Chemical Safety Board (CSB) and National Transportation Safety Board are great places to start researching what thorough investigations look like.
If you are feeling overwhelmed, I recommend you start by checking out the CSB investigation into a Millard Refrigerated Services Ammonia Release. You can download the report for free and there is even a video that gives an overview of the incident. As a result of the investigation, the CSB identified a variety of lessons learned about the physical design of the system, control system design, appropriate emergency response, etc. I like this example because it shows how a thorough investigation may require digging into a number of different areas.
This example also illustrates that there is often more than one useful lesson that can be learned as a result of an investigation (which is true for even more basic incidents or near misses). The number of useful lessons learned from this incident is a good example of what can be missed if an investigation focuses on finding THE root cause, instead of identifying ALL the causes that contributed to an issue (a systems thinking approach).
If you are interested in examples of investigations using the Cause Mapping method specifically, we have quite a few examples of Cause Maps of historic incidents available for free on our website or you can watch a recording of one of our case study webinars. The Titanic example is one of our better known case studies and would be a good place to start.
So, when is an investigation done? It really does depend on the specifics of each investigation. I can’t give you a simple rule to follow to determine when an investigation is complete, but there are resources available to help you get comfortable answering that question for yourself and your organization.