As you drive east on I-70 coming from the Rockies, there is a point where you seem to have stopped descending, but a sign says, “Trucks: Don’t be fooled. Four more miles of steep grades and sharp curves.” The message is that it would be premature to relax at this point, and vigilant driving is still required to safely reach flat ground.

Figure 1: Sign on I-70. Credit: Xnatedawgx, own work, GFDL

In the same way, when you are performing root cause analysis, you can reach points where everything seems to be OK. For example:
• You have found a root cause that is almost certainly contributing to the problem.
• The root cause you have found is actually a symptom and not the underlying cause.
• Your customer is no longer concerned about the problem.
• The problem seems to have gone away by itself, and nothing is happening.

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