As any Six Sigma green belt will tell you, use The Five Whys [1] The vehicle will not start. (the problem) Why? - The battery is dead. (first why)

As any Six Sigma green belt will tell you, use The Five Whys [1] The vehicle will not start. (the problem) Why? - The battery is dead. (first why) Why? - The alternator is not functioning. (second why) Why? - The alternator belt has broken. (third why) Why? - The alternator belt was well beyond its useful service life and not replaced. (fourth why) Why? - The vehicle was not maintained according to the recommended service schedule. (fifth why, a root cause) [1] https://en.wikipedia.org/wiki/5_Whys https://en.wikipedia.org/wiki/5_Whys