Some believe that providing a collection of rules of thumb is dangerous – dangerous
because engineers might forsake the fundamentals and place too much emphasis
on order-of-magnitude estimates. However, I have found for problem solving
in industry – for design, for process improvement and for trouble shooting –
rules of thumb are not dangerous; they are essential. From research on problem
solving, for example, we realize that skilled problem solvers create a rich internal
representation of the problem. During the creation of that representation, problem
solvers ask many What if? questions. They solve a simplified version of
the problem. They approximate. Rules of thumb are needed to do this well. As
we problem solve, research has found that we monitor our thought processes
frequently; we check and double check often. To do this well requires us to
have a rich set of rules of thumb. When we obtain an answer to a problem, skilled
problem solvers check that the answer sounds reasonable and that it answers the
initial problem. We use rules of thumb to do this. Rules of thumb are needed by
working professionals.

Download Here