• Formative evaluation;
  - helps to `form' ideas;
  - part of iterative design/RAD;
  - very difficult to manage.
  
  
  
• Summative evaluation:
  - at the end of development;
  - `9 out of 10' cats prefered it;
  - difficult to make sense of results.
  
  
  
• Post-summative evaluation:
  - monitor acceptance.