Understanding the Cone of Uncertainty in Agile Scrum


Navigating the Uncertain Waters of Software Development

When it comes to Agile Scrum in software engineering and development, there's one concept that stands out as a guiding principle in the initial stages of project management: the Cone of Uncertainty. This concept helps teams grasp the evolution of uncertainty throughout a project's lifecycle. In this blog, we'll explore what the Cone of Uncertainty is and why it's important in Agile Scrum. We’ll discuss how it can be useful in decreasing uncertainty and help achieve more accurate estimates, assist in risk management, and determine expectations for a given project.

The Birth of the Cone of Uncertainty

The Cone of Uncertainty wasn't always an integral part of Agile Scrum or project management.
The idea behind the "Cone of Uncertainty" actually started in the chemical engineering and construction world. It was first introduced by the people who founded the American Association of Cost Engineers, which is now known as AACE International. In 1958 they came up with a way to classify different types of estimates and how certain or uncertain they were. They even used "cone" diagrams to help illustrate this idea.
Later on, in the 1980s, a software engineer named Barry Boehm brought this concept into the world of software development and called it the "Funnel Curve." So, even though we often associate this idea with software projects now, its roots go all the way back to a completely different industry. (Wikipedia, October 2021) The concept was popularized, however, by Steve McConnell in his 1997 book "Software Project Survival Guide." He suggested this concept as a standard way to make educated guesses about the time and cost of a project, especially when dealing with a lot of unknowns. The Cone of Uncertainty helps us understand that while initial estimates might be a bit uncertain, they tend to get more accurate as the project goes on. Think of it like a funnel: wide and uncertain at the start, but narrowing down to more precise estimates as you progress through the project (Medium, Wicar Akhtar, 2022). Since then, it has become a cornerstone concept in Agile Scrum, serving as a vital tool for managing and navigating uncertainties in software development projects.

Cone of Uncertainty info graphic

RRslide, Aug 2021

Expansive Beginnings

Imagine standing at the beginning of a project, surrounded by a large and expanding cone of uncertainty. Your team has a general idea of project requirements and client needs for a given project, but it's too early to have a clear, definitive picture of the project's end goal. Consequently, estimating the time and resources required to complete the project accurately can be difficult to do. So, this initial stage is characterized by a wide range of potential outcomes and many different paths the project could take. It's like embarking on a journey without a map; you know your destination, but the exact route is still to be determined.

Gradual Constriction

When you first begin a project, there's a lot you don't know, making it the widest and most uncertain part of the "funnel." As your Agile Scrum project progresses, the Cone of Uncertainty gradually begins to narrow. The reason behind this narrowing lies in one of the fundamental principles of Scrum: constant feedback from stakeholders. As details about the project get sorted out and initial estimations have been refined, there is a gradual lessening of uncertainty, thus narrowing the “funnel” or cone. This feedback loop makes it easier to spot and correct any deviations or issues that may arise during development.

The more feedback you gather during the process, the more defined and certain your project becomes. This increased clarity allows your team to make more precise estimates regarding the time and resources needed to reach the project's completion. So, as you move forward the path ahead becomes clearer and the Cone of Uncertainty narrows.

Prioritizing in the Face of Uncertainty

The Cone of Uncertainty doesn't just serve as a progress tracker; it also helps your team prioritize its efforts effectively. When you find yourself at the widest point of the cone, your primary focus should be on gathering as many requirements and feedback points from the client as possible. This information is invaluable in making informed decisions and establishing priorities for the project. However, as the project moves closer to the narrow end of the cone, the level of uncertainty decreases. At this stage, decisions become more certain, and you have a clearer understanding of what the project needs to achieve the stakeholders' goals. This is the time to execute and refine with the confidence that your path is more well-defined.

Flexibility in the Face of Change

While the Cone of Uncertainty is an essential tool for understanding project uncertainty and progress, it should not be treated as undeniable truth. Depending on the nature of the project, the cone's width may fluctuate throughout the development process. This fluctuation occurs because project requirements can change due to the continuous feedback your team receives along the development journey of a project.

Sometimes, a project can take an entirely new direction midway, causing the cone to widen once more. Agile Scrum is built on flexibility and adaptability, so your team should always be prepared to inspect and adapt to changes during the development cycle. Embracing change is a key element of Agile methodology, and the Cone of Uncertainty helps teams do just that.

Conclusion: Navigating Uncertainty Towards Success

The Cone of Uncertainty is a valuable concept in Agile Scrum because it illustrates to your team how much you know about a given project and where you are in the development process relative to the completion, or the start, of a given project. By acknowledging the high uncertainty at the start, teams are encouraged to break work down into smaller, manageable chunks (sprints in Scrum) and tackle them iteratively. This allows for continuous reassessment and realignment and helps your team “see” the importance of iterative and incremental development, continuous communication and collaboration, flexibility, and adaptability. By monitoring the Cone of Uncertainty throughout a project's lifecycle, your team can make more informed decisions and manage uncertainties more effectively in terms of estimation of production requirements; business processes; timelines; and features. Ideally, at the end of a project uncertainty is eliminated and the scope of the project is confirmed.

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