Scrum vs. Waterfall

Reviewed by Bernie Maloney and Raúl Herranz

Scrum and waterfall are ways of managing work but represent very different approaches. One of the most important differences is scrum's frequent, incremental delivery of value, which makes it possible for teams to adapt to change when it appears on the path to creating a product.

The Two Approaches Defined

Scrum is an agile framework that:

• Uses flexible planning 
• Breaks work into smaller increments of value delivery 
• Regularly inspects and adapts to solve problems

Waterfall, on the other hand, is a sequential process that flows (like the cascades of a waterfall) through phases of a project and only moves on to the next stage when the previous is complete.

Depending on different variables like the team composition, the problem to solve, the type of product/service to deliver, and the context, one might be better than the other.

Key Differences Between Scrum and Waterfall

Waterfall Project Management

Waterfall is a project management approach in which people work on one stage at a time, and the next doesn’t start until the previous finishes. The stakeholder or customer requirements are set at the beginning of the project, creating a linear path for the project to follow. 

From those requirements, teams create a sequential project plan to accomplish them.

The stages of waterfall are:

• Gathering requirements
• Analysis and design
• Building or implementation
• Testing and validation
• Deployment and delivery
• Ongoing maintenance

Other characteristics commonly associated with waterfall are:

• Each stage of the project must be complete before starting the next
• Teams have specific skills and operate in isolation
• Each project stage corresponds to one team
• Fixed budget, scope, and schedule
• Little to no feedback from the end user until the entire project is complete and released
• Hard and expensive to introduce changes
• Can re-organize incomplete tasks but may cause delays

Overall, waterfall focuses on projects that have a specific set of requirements to accomplish a goal. Teams are not usually cross-functional; instead, they specialize in one skill. Teams may be highly dependent on each other's work. 

The Scrum Framework

In scrum, we shift to managing work as products instead of projects. While projects tend to have defined stages—as they do in a waterfall management approach, for example—product development and product management provide increments of a complete product on the path to a product goal.

Products can be goods, services, systems, applications, etc., created to resolve business problems or satisfy a customer’s need. Products are created by small teams who collaborate and are cross-functional, meaning each team has all the skills they need to complete the product.

Scrum began in software development but has evolved for various industries, including talent management, marketing, and hardware development. Scrum is an approach to deliver products that keep up with current, ever-evolving customer and marketplace needs.

At the granular level, scrum allows teams to increase effectiveness in their meetings, provides tools to track and measure progress, and requires a small cross-functional team structure to increase collaboration, transparency, and autonomy.

Scrum generally works like this:

• Work for a complex problem aligned to a product goal is ordered in a product backlog by stakeholders or the product owner
• The product owner and developers collaborate to define a goal for the sprint - something that frames why this sprint is valuable to the stakeholders.
• Scrum team selects work for the sprint consistent with the sprint goal
• An increment is completed by the end of a sprint adding value toward the product goal
• Scrum team and stakeholders inspect the results and adjust the product backlog for the next sprint
• Employs an iterative, incremental approach
• Optimizes predictability and controls risk
• Team members collectively have all the skills and expertise to do the work
• Teams self-organize and work towards a common goal
• Flexibility in scope
• Continuous refinement of functionality
• Values both team members doing the work and the end-user—not one over the other
• Allows for customer feedback along the way

Scrum also centers around three pillars: transparency, inspection, and adaptation.

Transparency means the emergent process and work must be visible to those performing and receiving it. Every part of the process should be clear for everyone on the scrum team. Low transparency can lead to decisions that decrease value and increase risk.

Transparency leads to inspection.

The artifacts of scrum, which are the product backlog, sprint backlog, and increments, carry the critical information needed during product development. They are inspected and revised regularly. Inspection happens during scrum events like daily scrum, retrospectives, and reviews. By regularly inspecting progress toward agreed-upon goals, teams will detect potentially undesirable variances or problems early.

Inspection enables adaptation.

Inspection enables teams to identify if any aspect of the increment is outside acceptable limits, doesn’t work correctly, or is otherwise deemed unacceptable. When the team understands the problem differently, they can learn new ways to adapt the product or their way of working to improve it.

For adaptation to work correctly, teams must be empowered and self-managing. That way, they can adapt the moment they learn something new through inspection to improve their work process and, in turn, the final product.

The goal of regular inspection and adaptation is to evaluate work done by developers to ensure a high-quality product.

When Is Waterfall the Better Model?

When the requirements for a project won’t change or are predictable, waterfall can be a more suitable choice. Industries with compliance requirements (e.g. government, banking, construction, pharmaceuticals) are often attracted to waterfall's phases. Waterfall's phases provide clear points to coordinate sign-offs.

Because of the waterfall method’s thorough, detail-oriented nature, it’s well-suited to teams working on projects involving multiple clients and stakeholders, when requirements are well-defined and there is minimal chances of them changing.

When to Choose Scrum

Scrum is best for teams with unclear or evolving requirements because of its flexibility and constant inspection and adaptation.

Scrum is ideal in software development, especially in today’s quickly evolving tech marketplace, because teams can deliver value in short sprints rather than waiting months or years for software to reach customers. 

Scrum is also well suited to many other industries, some of them highly regulated, including:

• Financial services
• Legal and consultancy
• Construction
• Data analytics
• Pharmaceuticals
• Engineering
• Marketing and advertising
• Education
• Event planning
• Military

The self-organizing teams of scrum can pivot on ideas without disrupting the product, and the focus on continuous improvement requires less oversight, fosters accountability, and leads to high-performing teams.

What About a Hybrid Scrum and Waterfall Approach?

Selecting the attributes that work best for your organization from each approach and making a hybrid model could be a way to tailor the approaches to your needs. A hybrid approach could benefit a waterfall-based organization by implementing agile practices a little at a time and seeing how they work.

As an example, if you were using a hybrid scrum and waterfall approach, it may look like this:

• Using a waterfall approach, build a first basic version of the product with limited features

• Use a scrum approach to refine the product, adding or updating the features to better align with the clients, users, and market needs

Potential Benefits of Multiple Approaches

It’s more challenging in larger organizations to overhaul every team into a new approach at once. Both methods could benefit these organizations with diverse groups with varying projects and management needs.

In addition, a digital agency or any consulting company being open to any approach would help because their clients may have a preference. To work with the client’s preference, you might need to be flexible enough to work with waterfall, scrum, or hybridization of multiple approaches.

Introducing scrum practices can help organizations adapt to changes and unexpected challenges during a product lifecycle. Sometimes they may need the rigidity of the waterfall approach, and sometimes the flexibility of scrum might be better.

Always Consider the Team, Product, and Organization First

Overall, depending on the organization, the project, the product, or end-user requirements, being open to achieving the best possible outcome instead of being stuck on the approach can be an excellent way for organizations to try different ways of working to see what works best for them.

An organization doesn’t necessarily have to be all scrum or all waterfall to see the benefits of each approach. Your selection of an approach should aim to improve business outcomes, create successful teams, and focus on delivering high-value work.

After all, inspecting and adapting working methods and seeing what works and what doesn’t is essential for any organization that wants to improve its work.

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