Management must provide employees with tools that will enable them to do their jobs better, and with encouragement to use these tools. In particular, they must collect data.

The only way to know how a complex system will behave-after you modify it-is to modify it and see how it behaves.

All models are wrong, but some are useful.

Remember that all models are wrong; the practical question is how wrong do they have to be to not be useful.

Statisticians, like artists, have the bad habit of falling in love with their models.

To find out what happens to a system when you interfere with it you have to interfere with it (not just passively observe it).

Just as the ability to devise simple but evocative models is the signature of the great scientist so overelaboration and overparameterization is often the mark of mediocrity.