Estimation

You cannot accurately estimate the cost of anything when cost determining quality attributes are unclearly defined.

1. The natural variation principle: All systems attribute can he expected to vary to some degree throughout the lifetime of a system.
   
   
2. The early bird principle: Any method which gives you early feedback and correction to reality is more likely to give you control over the final result than the big-bang methods.
   
   
3. The activist principle: Estimation methods alone will net change a result which is off the track. Active correction must be a part of your methodology. (Action, not estimation, produces results.)
   
   
4. The future shock principle: Data from a past project might be useful, but it can never be as useful to you as current data from your present project.