Part 2 of 2: Demonstration for Establishing an Efficient Project Portfolio Scheduling System to improve key performance indicators.
PPM Schedule Example
In order to understand the effect that scheduling decisions have on an objective function, consider five projects, characterised by the values given in the table below,
The portfolio manager can decide project delivery order and will consider the following six scenarios.
If the objective is to minimise the makespan i.e. the time it takes to deliver all projects, then all project orderings give the same solution – 170 days (the sum of all critical paths).
First-In / First-Out (FIFO)
If the objective is to process projects in the order they arrive, then a large weighted tardiness penalty results, which includes three tardy projects.
Earliest Due Date (EDD)
If the objective is to process projects in order of their due date, then the EDD schedule performs better than the FIFO schedule in terms of tardiness and weighted tardiness. However, the number of tardy projects remains the same for both schedules.
Shortest Processing Time (SPT)
If the objective is to process projects in order of their shortest critical path, then the SPT schedule performs better than the FIFO and EDD schedules and reduces the number of tardy projects.
Weighted SPT (WSPT)
If the objective is to process projects in order of their weighted shortest critical path, then the WSPT schedule performs the same as the SPT schedule, which, is not always the case.
If the objective is to minimise the number of tardy projects when the importance (weight) of all the projects are considered equal, then Moore’s schedule results in the best performing tardiness and weighted tardiness values, and only one tardy project.
The results of the different scenarios are summarised below,
Compared to the weighted tardiness FIFO schedule, the EDD schedule results in an 8% improvement, while the SPT / WSPT schedules result in a 16% improvement and finally the Moore schedule represents a 40% improvement! While there is a 67% improvement in the number of tardy projects!
Therefore, depending on your project portfolio objective – time, cost, resource or some combination thereof, very different scheduling improvement results can be achieved. Unfortunately, since every project portfolio is unique no one priority rule is optimal meaning all priority rules need to be tested and compared.
If you would like to receive the Excel workings for this Blog else would like to know more about leveraging data-driven actionable insights for your project portfolio, then feel free to contact me on email@example.com
About Ian: I have more than 20-years IT Project Portfolio experience spanning vendor, solutions integrator and customer side both for private and government organisations. I have worked for Motorola, Ericsson, Vodafone, Dimension Data and Fujitsu amongst others. I am the principal of pminsight, a boutique consultancy specialising in empowering project organisations and professionals with project data-driven insights.