Wbs Building Use This
- 1. Project Management Dr. James A. Bednar jbednar@inf.ed.ac.uk http://homepages.inf.ed.ac.uk/jbednar SAPM Spring 2006: Project Management 1
- 2. Project Management A project is ‘a temporary endeavour to produce a unique product, service, or result’ (PMI 2004). Project management (PM) techniques were originally developed for waterfall-type projects like building construction. PM focuses on planning, scheduling, monitoring, and controlling the complex interdependencies among subtasks. PM techniques are particularly relevant when considering the entire project in which software development is embedded, which includes other activities such as documentation, training, hardware, etc. SAPM Spring 2006: Project Management 2
- 3. Example project Consider building a garden Roof shed, which involves Framing designing the shed, figuring out what materials Siding are needed, ordering or purchasing the materials, and putting together the Foundation various parts. Some of these tasks depend on the others, some must be scheduled, some take labor, etc. SAPM Spring 2006: Project Management 3
- 4. Project management tasks Need to figure out: • What needs to be done • What order they can be done • How long each will take • How long the whole project must take in principle • How long the whole project is expected to take, given finite resources SAPM Spring 2006: Project Management 4
- 5. Work Breakdown Structure A WBS is a diagram showing the major subtasks of the project: Build Shed Planning Obtaining Materials Constructing Pour foundation Build frame Install siding Install roof Finish (door, etc.) Rule of thumb: break things down as far as necessary to estimate and schedule them, and no further. SAPM Spring 2006: Project Management 5
- 6. Network diagram Build Shed Materials list Order materials Deliver materials 1 day 1 day 1 day 7 days Install siding 1 day Pour foundation Build frame Finish 1 day 2 days Install roof 1 day 2 days Network diagrams can be constructed from the WBS, adding dependencies and estimated durations. See slides on estimation for caveats. (Dates are optional.) SAPM Spring 2006: Project Management 6
- 7. Critical path Build Shed Materials list Order materials Deliver materials 1 day 1 day 1 day 7 days Install siding 1 day Pour foundation Build frame Finish 1 day 2 days Install roof 1 day 2 days The critical path is the longest path through the network diagram – it is the minimum duration of the project if there are infinite resources (so that tasks can occur in parallel) and accurate estimates. Here, everything but putting up the siding is on the critical path, and must happen in the order specified. SAPM Spring 2006: Project Management 7
- 8. Slack Build Shed Materials list Order materials Deliver materials 1 day 1 day 1 day 7 days Install siding 1 day Pour foundation Build frame Finish 1 day 2 days Install roof 1 day 2 days Tasks not on the critical path have slack – the duration by which they can be late without making the project later than the critical path duration. Here, putting up the siding has one day of slack: one day longer than estimated is ok, but if it takes longer it will be the new critical path, and delay the project. SAPM Spring 2006: Project Management 8
- 9. PERT/CPM Charts Network diagrams come in a variety of flavors with different names: A Program Evaluation and Review Technique (PERT) chart shows dependencies and time estimates, using 3-point estimates. The Critical Path Method (CPM) chart is a related alternative, using single estimates. Both show similar information, but use different methods for calculating the critical path and slack. SAPM Spring 2006: Project Management 9
- 10. Gantt Chart A Gantt chart shows the tasks and their durations graphically, in calendar form, with one bar per activity. The bar shows the earliest start date and duration. SAPM Spring 2006: Project Management 10
- 11. Gantt Chart extras Gantt charts can also show summary activities (see ‘Planning’ entry), dependencies (arrows), and milestones (diamonds). The dependencies make slack clear (see “Siding” entry). SAPM Spring 2006: Project Management 11
- 12. Resources All these charts assume infinite resources – things that can logically happen in parallel, are assumed to happen in parallel. In reality, there are limited resources, so there are dependencies not shown in the charts. E.g. if only one person is available to work on the shed project, the siding and roofing tasks must be done in serial, due to the resource constraint. SAPM Spring 2006: Project Management 12
- 13. Crashing/Fast tracking If the critical path is still not fast enough, it’s possible to shorten the duration by changing some assumptions. E.g.: Crashing: Change the duration of some critical task, e.g., if it is possible to parallelize it by assigning more people to it. Fast tracking: Allow tasks to be done in parallel by changing the logic in the network diagram. If tasks can be parallelized (as in building construction) these allow total duration to be greatly reduced. SAPM Spring 2006: Project Management 13
- 14. For more info Project Management Institute (PMI): Largest international PM organization; US-based (pmi.org) International Project Management Association (IPMA): Oldest international PM organization (www.ipma.ch) Association for Project Management (APM): UK-based national organization (www.apm.org.uk) PM Glossary: www.maxwideman.com/pmglossary/ SAPM Spring 2006: Project Management 14
- 15. Summary • Project management charts and techniques are useful for scheduling tasks with complex dependencies • WBS: main tasks • Network diagram: dependencies, durations • Gantt: calendar • Be careful not to trust the charts just because they look fancy; e.g., many constraints are not shown SAPM Spring 2006: Project Management 15
- 16. References PMI (2004). A Guide to the Project Management Body of Knowledge (3rd Ed.). Project Management Institute. SAPM Spring 2006: Project Management 15