Before evolving into the form as we know it today, RCA first made its appearance in the field of engineering. Much like lean manufacturing, the beginnings of RCA can also be attributed to the management philosophy instituted by the Toyota Production System (TPS). One of the key contributions of Sakchi Toyoda along these lines was the formulation of the “5 Whys”. The basic underlying premise here is asking “why” five times consecutively to arrive at the core of the problem.
For instance, let’s assume the internet is down. These would be the 5 Whys you would ask:
- Why is the Internet down? Because the DSL light on the router is not stable and is flashing intermittently.
- Why isn’t the DSL light stable? Because there could be an issue with either the line coming in from the filter, or with the line coming from the junction box outside. You’ll then want to check the jacks and cables involved.
- Why is there an issue with the filter? – Because it could have either gone bad or might have a loose connection – [Try replacing filter or directly connecting the jack.]
- Why is it still not working, despite changing the filter or replacing the jack? – Because this could be an issue with the line coming in from the junction box. – [Get someone to check the junction box]
- Why is it not working despite everything being fine in the local junction box? – Because there is an outage.
So, typically the 5th why would lead to the core of the issue.
This example is one of the more simplistic forms of RCA, but differing models can vary in their complexity.
In 1986, Motorola developed a new strategy called Six Sigma. This was primarily built around enhancing risk management. It employed specific methods and statistics to outline RCA. Six Sigma also refers to the highest quality attainable which roughly translates to about 3.4 errors or defective products per million.