The debate: Agile versus Waterfall

The longstanding rivalry between Agile and Waterfall processes is really over the primacy of scope in a project. Reputably, Agile’s iterative process delivers milestones more frequently, which is ideal for less-defined projects, however Waterfall’s scope-led position lends itself to better governance for those projects with concrete deliverables.

Both methods have challenges. Agile relies heavily on exceptional teamwork and some organisations do not have this capability; Waterfall focuses on getting the project done, sometimes to the detriment of stakeholder buy-in. Which is best? These two advocates will plead their case.

The case for Agile

Aoife Morley has spoken about Agile at conferences including the IPMA World Congress.

Agile is…
A set of guiding principles for building software, often called iterative development. Scrum, Kanban and XP fall under the Agile umbrella. These methods have rules, while Agile is based on 12 principles. For software development projects there is no better alternative to using Agile to deliver early and frequently while adapting to customer requests.

Only Agile would do for…
An application development project I once worked on. Neither the developers nor the business understood the potential of the app or its use for a particular customer. Two-week iterations were ideal for experimental development. The developers built to the business needs, received feedback, agreed on changes and moved onto the next iteration without wasting time on an unsuitable product. It would have been impossible for the business to communicate exact requirements and sign off on a scope document at the start. Even when we meet exact customer requests, such as in Waterfall projects, often the customer left feeling dissatisfied.

However…
I’ve felt it necessary to steer some clients away from, or postpone, Agile initiation. Lack of knowledge, experience and support can often lead to misunderstandings of the intention of Agile. Where there is a cross-functional, self-organising team, the benefits of an Agile project can be significant.

Agile is best…
For projects where scope change is expected. Cost effective early delivery of value to the business can be achieved through regular iterations, keeping the customer close to the project and providing rapid reaction to inevitable change. An Agile project values customer satisfaction as a priority. This leads to the delivery of a product that best reflects what the customer needs, not what they may originally say they want.

The case for Waterfall

Pedram Danesh-Mand is a Director at KPMG.

Waterfall is…
A sequential delivery process where progress flows steadily downwards, like a waterfall, through feasibility, conception, initiation, design, construction, commissioning, and maintenance. Initially from the manufacturing and construction industries, the Waterfall approach models highly structured physical environments in which changes are deliberately kept to a minimum.

Only Waterfall would do for…
Logic-driven (compared to resource-driven or system-driven) projects including construction, manufacturing, vendor software installation and public works utilities. The scope can be set upfront through requirements with cost, schedule and performance as variables.

Time spent early on understanding and defining scope, alongside proper documentation, will considerably mitigate future delays, cost overruns, claims and disputes. It also offers transparent, upfront identification of risks and uncertainties as well as clear allocation between different stakeholders.

However…
It is not ideal for projects where an evolutionary approach is required. These types of projects may have changing client requirements or an undefined endpoint, for example, where the client can choose to accept a less-than-complete outcome if enough of the requirements have been met. If the cost, schedule and performance can be set upfront with the scope as the variable, approaches other than Waterfall might be more suitable.

Waterfall is best…
For delivery of complex projects. This approach proactively identifies and manages risks and uncertainties of the project and brings it the highest probability of success.

Any approach should always be selected with consideration of the client’s ultimate goal, which obviously depends on the organisational culture as well as how the client defines success or failure. Waterfall will work best for the needs and capabilities of most clients, particularly those who can identify key requirements upfront.

Interviews by Adeline Teoh