Facts and fallacies of software engineering

Facts

• The most important factor in software development is the quality of the programmers.
  
• The best programmers are up to 28 times better than the worst.
  
• Adding people to a late project makes it later.
  
• One of the most common causes of runaway projects is poor estimation.
  
• The other most common cause of runaway projects is unstable requirements.
  
• Requirements errors are the most expensive to fix during production.
  
• Maintenance typically consumes 40 to 80 percent of software costs.
  
• Enhancements represent roughly 60 percent of maintenance costs.
  

Fallacies

• Software needs more methodologies.
  
• You teach people how to program by showing them how to write programs.
  

Adapted from Robert L. Glass, Facts and Fallacies of Software Engineering, Addison Wesley, 2003