You have to have a business case to start, as you do more discovery and feasibility you UPDATE the business case and charter document forms to then also evolves as the project progresses. Saving Changes...
Anonymous
You typically start with a concept, then a feasibility study, then a business case (which is the documented economic feasibility study that is used to establish the validity of the outcomes & outputs or the benefits to be delivered). This would be used later to build the project or program charter (as applicable).
The business case may be considered as the primary justification document for an investment decision. It describes the success criteria that is to be maintained throughout a project or program. The variance between the achieved and the planned outcomes is used to calculate the success of the project or program.
So the feasibility study is used as an input to the business case. The business case serves as a formal declaration of the benefit / value that the project or program is expected to deliver and a justification for the resources that will be expended to deliver it.
With that being said, you may still carry out a feasibility study post the business case to assess the organization's financial, sourcing, complexity and constraint profile. This is typically done on programs. Consider it as a revision / elaboration to the high-level feasibility study executed earlier.
This is PMI's process. What most of us do is more or less the same. Just think of process and do not get hung up on the terminology.
