Product-based approach
This approach emphasises products (or deliverables)
rather than tasks
The PRINCE method uses a product-based approach
There are two diagrammatic tools
Product-based approach
The Product Breakdown Structure (PBS) is similar to a Work Breakdown
Structure, but...
- the elements are products not tasks
and more importantly
- a PBS is devised from those products (deliverables) we know we must
produce - contractually required
Products to be included in a PBS are
- technical (what the customer needs)
- quality (QR documentation, requests for change)
- management (plans, record of meetings etc)
Example of a PBS
A critical path diagram shows which tasks must be complete before the
next starts. The Product Flow Diagram shows which products must be complete before
the next can be produced
- Most items in the diagram are things the customer needs
- design documentation, software, manuals
- Some items are intermediate products, needed only to help produce
other products
- first cut database design
both indicated by boxes
- Some items will exist already
- feasibility study report
- terms of reference
indicated by elipses (ovals)
- Arrows indicate that one product is required in order to produce the
next
Example of a PFD
Turning a PFD into a CPA
We will need at least one task to make each product. We may
also need another task to bring components of composite products together.
Every product will require a quality review meeting
Task dependencies will either be:
- taken from the product flow dependencies; or
- a chain of tasks to make one product
Turning a PFD into a CPA: example
Product-based vs. task-based
Product-based
- complete
- verifiable against requirements documentation or contract
- not reliant on individuals to invent tasks
- any number of levels (WBSs have fixed length codes)
- define stages from the PFD
Task-based
- tasks more natural
- some tasks - such as training - don’t have an obvious "product"
- define stages from the WBS
Other topics