5-WHY Decomposition Methodology

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The ‘Five Whys’ is the simplest method for root cause analysis. Take each presumptive cause and ask ‘why’ continuously until you exhaust that line of questioning. (Five Whys is the most commonly used method for determining root cause. The root cause is usually found by the fifth ‘why’ but can take more or less iterations, depending on the problem.)

Note: If there are multiple presumptive causes, you should complete the ‘five whys’ for each one.