Highlight from 'The Principles of Product Development Flow' by Donald G Reinertsen

We want to control measures of performance that have strong influence on economic success. We can identify these parameters using the economic framework discussed in Chapter 3. If a 10 percent increase in project expenses reduces profits by 1 percent, and a 10 percent increase in unit cost reduces profits by 50 percent, we should focus our attention on controlling unit cost, not project expenses.