Thank you for the references, will check it out.
Jyothi Rangaiah

To me the SDLC starts when the development project starts — when we have some-what fixed requirements or begin development sprints from an established backlog. Depending on context obviously. I have a bit more about it here:

Scott mentions how we can add value in establishing the business case and business ideas. These can be tested/challenged. Some business schools teach classes in simulations and experimentation with business ideas. Something along these lines: but also in rapid prototyping there is always an implicit scientific model (hypothesis/trial).

In essence: The PO’s how do the decide, how do they choose one item over another. What assumptions and probes do they take when deciding?