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The Cone of Uncertainty – The Basics
By Michelle Symonds

The Cone of Uncertainty is a well known theory which was developed by Mr Barry Boehm in the early 1980’s. This concept was introduced in the book titled Software Engineering Economics.

The Cone of Uncertainty relates to the aspects of uncertainty within project management and how they evolve throughout the process. Often when a project is in its infancy, it is impossible to accurately predict how the work will progress, estimations cannot be precisely predicted and so the project is subject to uncertainty. As the project develops, research is undertaken in various areas and more details can be obtained allowing those involved to gain more information therefore decreasing the overall level of uncertainty. This reaches 0% when the continual risk has been accounted for or eliminated with risk management strategies.

The closing of the project should involve these risks being eliminated or responsibility for management of these risks transferred to a group dedicated to the ongoing maintenance of the project. This term is often used within industries where the business settings, technical settings or general environment are subject to quick changes. Industries like software development often use this term. Although it can be referred to under the title of different names, it remains a well known core principle of cost engineering which is an engineering practice revolving around and dedicated to the management of project costs.

The majority of environments advance at an acceptable, gradual speed which means they are treated as passive and the basic PM strategies can focus on analyzing the environment and devising a plan to fully understand it. Before a stakeholder fully invests, the level of uncertainty is depleted and assessed allowing the uncertain prospect or risk to be adequately contained and carried. In this particular setting the unknown risks deplete at speed primarily, which means the shape of the cone is not pronounced initially.

The field of software is unsettled and unpredictable which means the pressure to decrease risk factors comes from within the industry as well as within particular projects. Individual project managers and their team must effectively work towards the reduction of uncertainty within the project on a continual basis.

The term is constricted by gathered information and team/PM discussion and decisive action which enables any project variations to be removed. Taking decisive action based on outlook and capacity including factors that are internal and external in relation to the project means the cone shape will stay the same, if those actions or decisions change at any point, the cone broadens.

The cone of uncertainty has various applications within sales, HR and staff selection and investments. Essentially it describes the common phenomenon of project uncertainties decreasing throughout the duration of the project. Having the knowledge to use the Cone of Uncertainty as part of your PM toolbox – particularly if you’re involved in IT projects – is an invaluable resource that can be learned on many project management courses such as those for the APMP qualification. Counteract the Cone of Uncertainty using risk management which considers a range of projections, improvement of projection processes, upgrade of a development model and continuously look over these estimations throughout the entirety of the project.

Michelle Symonds is a qualified PRINCE2 Project Manager and believes that the right project management training can transform a good project manager into a great project manager and is essential for a successful outcome to any project.

There is a wide range of formal and informal training courses now available that include online learning and podcasts as well as more traditional classroom courses from organizations such as Parallel Project Training.

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