Toyota understands that stages 1 – 4 are key to ensuring the right problem is tackled and in the right way. Problems can get messy and convoluted so it’s often confusing to teams as to which specific aspect of a problem to focus on. Step 1 and 2 are important to stratify data, often using Pareto to breakdown the problem. Asking what, when, where and who helps to highlight the top issue to be tackled. It then becomes easier to set SMART targets for improvement. Stage 4 and the identification of root cause is, arguably, the most difficult and the most poorly executed. Here Mark took us through a detailed process to move from the prioritised problem to possible direct causes. The mistakes are to jump in and prescribe possible direct causes to the problems without going to Gemba to confirm the facts. Here direct cause – observed causes of the problem - and root cause – the actual end cause we are trying to identify - are often confused. And then the use of the ‘5 whys’ , a simple tool, which is so effective in drilling down the causality chain to the true root causes.