One of the principal goals of theÂ Toyota Production System (TPS)Â is to identify steps that add value (and those which do not) and then design out waste.
Muda is one of the three types of waste (the other two being muri and mura) and the one that has been given the most attention since the TPS has been widely studied. Of this type of waste,Â Taiichi Ohno further identified the seven wastes:
While reading this I also came acrossÂ Mottainai â€” a Japanese term meaning “a sense of regret concerning waste when the intrinsic value of an object or resource is not properly utilized”. I like that.
Five Whys is “a question-asking method used to explore the cause/effect relationships underlying a particular problem. Ultimately, the goal of applying the 5 Whys method is to determine a root cause of a defect or problem”. Developed by Taiichi Ohno–one of the inventors of the Toyota Production System–the oft-cited example is as follows:
My car 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 has never been replaced. (fourth why)
Why? – I have not been maintaining my car according to the recommended service schedule. (fifth why, root cause)