Validation

• How do you know if the system works?
• It's not just a question of whether it runs. It needs to give the right answers.
• You can do a two fold test, or keep some cases as validation data.
• You need to be careful with this so that you don't use the validation data to develop the system.
• This is a complex form of testing.
• You can have a tester separate from the developer.
• You want to keep data away from the developer, so that the system is generalizable.
• What you really want is for the system to work on new data.