I have been thinking about the value of incorporating resources into schedules for some time. At one level it’s not too hard to do but is it useful?
From one aspect, it is impossible to schedule at any level without the active consideration of resources. Resources do the work in a given time and changing either the quality or quantity of the resource has some inevitable impact on the duration of the work. Consequently, it is critical to know the resource assumptions used in planning to validate the schedule and more importantly understand deviations from the plan during the execution of the work.
Generally what I mean by term ‘considered’ is the basic need to know the resources needed to undertake the work on every activity:
These decisions also need to be recorded and monitored. How much detail is recorded in the scheduling tool and what scheduling functions are used though is an altogether different question – this I refer to as ‘quantitative’ resource analysis.
Consideration is not the same as quantitative analysis within a scheduling tool. Quantitative resource analysis requires answers, or assumptions to be made, about a range of uncertain issues. Some of the nearly insoluble questions include:
These unanswerable questions are complicated by the fact all scheduling software fails to optimally level resources. Basically the tools get it wrong; the only question is how wrong: some are not too bad others unmitigated disasters. Resource scheduling needs both knowledge and common sense – no software applies common sense yet. But we have to plan resources – they need working space, accommodation, etc. And resources are the source of all cost expended on the project!
Another really interesting factor is the emerging understanding of the interaction between the schedule and the behavior of people. IF the people believe the schedule represents a realistic approach to their work, they will (and do) modify their behaviors to conform to the schedule to be seen as successful. Obviously if resources are included in the schedule it is far more credible than if they are not. This was touched on in Scheduling in the Age of Complexity (read from p19 – the rest is not relevant and it’s a horribly long paper).
So in summary I would suggest, consideration of resources is critical, as is having some form of method statement; together they dictate the planned durations of the work.
However, whilst using scheduling tools to calculate and level resource demands is useful, and can help gain valuable insights, you need real skill on the part of the scheduler and the right tools to achieve sensible results. Regardless of the skills of the planner, KISS (Keep It Sweet and Simple) is an important aspect of effective resource planning. It is only useful to planning resource requirements at a level of detail that is appropriate for real management needs. But the basic issues remain; you cannot rely on a scheduling tool to optimize the duration of a resource leveled schedule.
We use a basic network in our Scheduling courses that very few software tools get ‘right’ and optimize the project outcome. The answer to achieving the shortest overall duration is starting the critical resource (Resource 3) as soon as possible. To achieve this Resource 2 has to focus 100% on completing Task B as quickly as possible BUT, Task C is on the Time Analysis critical path not Task B and 99% of the time software picks C to start before B delaying the overall project completion.
This is not a new problem, a paper by Kastor and Sirakoulis in the International Journal of Project Management, Vol 27, Issue 5 (July, 2009) p493 has the results of a series of tests – Primavera P6 achieved a duration of 709, Microsoft Project 744 and Open Workbench 863.
When Kastor and Sirakoulis adjusted the resource leveling settings in P6 and its results were 709, 744, 823, 893 – a huge range of variation and the best option (P6) was still some 46% longer than the time analysis result. Other analysis reported in the 1970s and 80s showed similar variability of outcomes.
As Prof. George Box stated – All models are wrong, some are useful… the important question is how wrong does the model have to be before it is no longer be useful.
Computer driven resource schedules are never optimum, done well they are close enough to be useful (but this needs a good operator plus a good tool). And good scheduling practice requires knowing when near enough is good enough so that you can use the insights and knowledge gained to get on with running the project. Remembering even the most perfectly balanced resource schedule will fall out of balance at the first update…..
My feeling is the value of the process to the development of a realistic and achievable schedule depends on the circumstances of the project.
The ultimate solution is more viable scheduling tools that are capable of proper resource optimization; these are beginning to emerge and are the focus of my paper Resource optimisation - a new paradigm for project scheduling, it is still a work in progress but there has been a lot of useful feedback.
What is your take on resource scheduling?