pminsight is a boutique consultancy specialising in advanced planning and scheduling services for project organisations and professionals.
It’s a way of determining how to better handle situations where clients are waiting to be served. Queuing models are used to determine the average wait time and the average queue length. These measures are used to assess customer satisfaction and how well resources are utilised. Queuing theory is based on three things,
Queuing models are represented using Kendall’s A/B/C notation,
K, N and D were later added to the model to make it A/B/C/K/N/D
In most models, K, N and D are assumed to be,
There are three common notations that are plugged into the A and B variables,
There are four different queuing model types,
The project arrival and project delivery rates are modelled. Also, modelled are the number and type of project resources and the design of project services offered. Marketing and psychological data needs either be estimated else gathered to ensure the abstract model reflects reality as closely as possible. Having developed a model, it can then be experimented with to determine how changing different factors affects client outcomes, which then leads to an optimised model.
Project organisations constantly struggle between quality of service provided versus the efficiency of operations. Considerations of resource supply versus project demand is a dynamic activity reflecting uncertainty in project arrivals and how projects perform. Further complications involve resource capacity versus capability which is dependent on the nature and types of projects in the portfolio. Queuing models help balance these considerations by incorporating the economic impact of adding more staff versus what the market is will to pay.
Queuing theory helps project organisations hire new resources and schedule projects. During any given project, a certain skill may be in demand and for proper staffing you need skill sets to overlap so all client needs can be met at any given time. When modelling organisation capacity it is tempting to assume a best-case scenario however our experience indicates it is better to set the floor for minimum capacity and then anything chargeable and billable over and beyond this is a bonus. A further tip is to account for public holidays, annual leave, training and sick leave.
It is not possible to rely solely on queuing theory for optimal solutions for planning project services. The old adage, “all models are wrong, but some are useful” springs to mind. Models are an abstraction of reality and hence do not perfectly model all real-life scenarios. Consequently, while underlying patterns of project service can be modelled, not all real-life scenarios follow an exact pattern, which can result in unpredictable behaviour and results.
Research shows that how people “feel” while waiting in a queue matters more than the length of the wait. In other words, the “experience” of waiting is more important than the actual “time” spent waiting. By leveraging knowledge on the psychology on queuing, you can ensure customer user experiences are always positive.
Five signs your organisation is not only ready but in need of a queuing model,