I have seen this discussed briefly in the Corp. Fin thread and it seemed there was some debate. I wanted to pull it out to seek clarification.
If you have a project w/ a positive NPV,
1. you certainly do not adjust the NPV for a sunk cost, such as say, the development of a prototype. (No NPV adjustment)
2. if you are considering the possibility of delaying the project, you do not adjust the NPV because the decision to delay is an option that has value. since the original project has a +NPV the addition of this option would only add value and not cause you to reject. (No NPV adjustment)
If you have a project w/ a positive NPV,
1. you certainly do not adjust the NPV for a sunk cost, such as say, the development of a prototype. (No NPV adjustment)
2. if you are considering the possibility of delaying the project, you do not adjust the NPV because the decision to delay is an option that has value. since the original project has a +NPV the addition of this option would only add value and not cause you to reject. (No NPV adjustment)