Under the lean system, any tools which are required for solving problems are used.

To assure the prosperity of a firm should be a long-term strategy and the turnover of key managers should be taken into account from the stand point of long-term consideration and not from the monthly or quarterly flavors.

Progress is impossible without the ability to admit mistakes.

It is impossible to improve any process until it is standardized. If the process is shifting from here to there, then any improvement will just be one more variation that is occasionally used and mostly ignored. One must standardize, and thus stabilize the process, before continuous improvement can be made.

The standard is not writ on the stone. The definition of the standard is that it is the best way to do the job for now. It should be regarded as a next step to make further improvement.

Control charts are one of the statistical tools for solving quality related problems.

There are various non-statistical tools that have been typically developed by lean companies, notably by Toyota for minimizing variability in production, such as standardization, introduction of takt time, synchronization, shortening the total production lead time which I am fond of referring to as non statistical tools.