Priority - how sensitive the profit is to changes in schedule.

Do we want to apply effort in testing (More time)? or Do we take the risk of rework (More Money)? 

To be able to compare we need to use the same unit of measure to take an informative and intelligent decision..... sometimes the Cost of Delay is so high that you must take the risk of rework. By understanding the cost of delay you are able to take and make the correct economic choices. You are able to prioritize because you know how sensitive the profit is to changes in features and schedule.

Don Reinertsen at GotoConference - The Tactical and Strategic Art of Economic Models. 

http://www.infoq.com/presentations/Economic-Models 

Some Key points in the presentation:

• We are ignorant about our economic models and unaware of our ignorance - we need to learn more to take better and faster decisions.
• If you ask people who can delay a product, what they think it would cost to our stakeholders if this product is delayed by sixty days? You would get 50:1 responses...... someone saying 1000 to someone saying 50000. The problem is that If you dont know the Cost of Delay, you would do different *choices* if you think the number is different.... 
• If everybody understand the cost of delay they can take and make the correct economic choices at all levels - not only product managers. 
• Priority - how sensitive the profit is to changes in schedule.