I am not much given to regret, so I puzzled over this one a while. Should have taken much more statistics in college, I think- Max Levchin, Paypal Co-Founder

Probability and statistics is the basis of all decision making in the presence of uncertainty. Since all project work operates in the presence of uncertainty, we need to apply probability and statistics to those decisions. By definition probability and statistics is based on estimating the future outcomes of any models using empirical data. These estimates are models in their own right.

To Not Estimate is to willfully ignore the principles of probability and statistics of decision making