Scrum vs. Waterfall: Which is right for your project?

In order to be able to present a finished project, there are different procedures that can support you. Which way is chosen depends on the type of the project. Two possibilities are the Scrum Framework or the Waterfall model, which differ greatly in their implementation since they are suitable for different types of projects. The question is which projects these are and how to plan with these two approaches.
A person draws a seesaw. On one side is A, on the other B.


The basics of the Scrum Framework and the Waterfall model

Unlike the Waterfall model, Scrum does not require full planning documentation. This means that there is no strategy to be followed to the end. There is a Product Goal to be achieved, which describes the concrete goal and follows the development of the current product. Based on this, a collection of prioritised tasks, User Stories, etc. is created in the Product Backlog, which sets requirements for the product that are implemented step by step in short Sprints. These are limited in time, lasting no longer than a month, and in it all Scrum Events are processed, and the Product Owner's ideas are implemented. When a Sprint is completed, a new one is started immediately, with customer feedback obtained beforehand so that any adjustments can be made. To ensure a smooth process, there are rules and values that everyone has to follow to achieve the big goal in small steps. 
In the Waterfall model, the project is divided into phases that build on each other in a linear fashion. At the end of each phase, the previously defined work steps are reviewed to ensure that they have been delivered on time and on budget. If acceptance is successful, the next phase begins. The sequential approach is intended to avoid regression, but this can lead to exponentially increasing costs if changes are made to the project, which will be discussed in more detail later.

Main features of Scrum and Waterfall contrasted

As already mentioned in the previous section, the two approaches differ in their implementation. Not only do they differ here, but also in team composition, timing and process.

Composition of the team

In the Waterfall model, there is a project manager who is responsible for the technical management of the team and for keeping to time, quality, and cost, as well as for the stakeholders. In contrast, the Scrum Team consists of the Product Owner, who may be the customer or a representative and who ensures that ideas and requirements are integrated; the Scrum Master, who provides a conducive working environment and ensures that Scrum is implemented optimally; and finally, the Developers. Developers in Scrum Teams come from different departments and are cross-functional. They work independently and have the overriding goal of delivering value after each Sprint. The Product Owner, Scrum Master, and Developers work together to produce the best possible product.

Adaptability vs predictability

In Scrum, the path is defined step by step, i.e., after each Sprint, it is checked whether the goal has been achieved. There are always feedback loops, which means that the project can be constantly adjusted. In this way, the product can be better adapted to the needs of the Product Owner, and unforeseen events can be accounted for. However, this also means that planning reliability is not particularly high. The Waterfall model, on the other hand, is very predictable because the path is set from the beginning, which allows for a high degree of predictability. Before the project starts, the team and the project manager sit down and define the objectives, purpose, scope, and outcome. At the same time, the requirements of the project and the expectations of the stakeholders are clarified. This way, everyone knows what needs to be done and when, and what requirements need to be met by the end of the project. This, in turn, hinders adaptability.

Iterative vs linear

Iterative means that a process is repeated frequently, while linear means that something goes in a certain direction without digressing. 
It can be concluded that iterative planning in Scrum means that a Sprint has a limited duration of ideally no more than four weeks before the process is repeated with new goals. At the end of each Sprint, a Sprint Review takes place to check whether the goals have been achieved or whether adjustments are necessary. 
The Waterfall model is exactly the opposite. This is because it is strictly linear. That means that at the beginning there is a conception phase, where the goal is defined, and the path is determined. This is followed in a linear fashion, with no deviations. Adjustments can only be made at the end, because the project is not reviewed beforehand.

Scrum or Waterfall - examples of suitable project types

First of all, a project can be distinguished from a routine activity by conducting a project check. If this reveals that it is a project, the right project management approach must be found. A general question can be whether there is a defined goal at the beginning of the work, which includes a rough idea of the final product. If the idea is rough and still leaves a lot of room for adjustments, Scrum can be used. But if everything is already precisely defined and no more adjustments are needed in the course of the project, one can fall back on the Waterfall model.
Another good tool to assess which approach should be chosen is, for example, the Stacey Matrix. On the one hand, this can serve as a decision-making aid for complex issues, and on the other hand, to find the right approach. Depending on the requirements, projects can be divided into four areas: simple, complicated, complex or chaotic. Roughly summarised, one can say: If there is a high degree of planning certainty and the goal is clearly defined, the project is simple and a classic model such as Waterfall can be applied. This can be, for example, government projects such as the construction of a school, where budget and schedule can be planned exactly, or short projects in software development such as the development of a website, where changes do not take too much time.
If, on the other hand, there is low planning reliability, the goal has not yet been fully worked out and there may also be a lack of agreements and decisions, the project is rather chaotic and falls within the scope of Scrum. An example of this would be the development of apps. Our time is so fast-moving that new products are constantly coming onto the market. Therefore, while working on a product, it is important to simultaneously observe how the market is developing and what adjustments need to be made.
The transitions between the individual bullet points are fluid, however, a project cannot always be assigned to just one or the other division. The model therefore also shows that sometimes hybrid approaches, i.e., a mixture of Scrum and Waterfall, have to be used.

The advantages and disadvantages of Scrum and Waterfall

Both Scrum and the Waterfall model have advantages and disadvantages that can be derived from the structure of the planning. It is also possible to conclude which type of planning is better for which type of project or company, or whether a mixed form is better.

The advantages of Scrum

The advantage of the framework is the high flexibility due to the short Sprints. This means that the product features are always implemented on time, and the project can always be adapted as problems can be responded to quickly. The team's own responsibility also ensures a high level of efficiency, as the team members organise themselves and thus also strengthen the team. Regular meetings, such as the Daily Scrum, which should last no longer than 15 minutes, keep everyone up to date.

The advantages of the Waterfall model

Because the project is fully planned by the project manager from the outset, the project completion date, budget and deliverables can be stated with relative certainty. In addition, because of the linear process, the flow of the model is clear and unambiguous for everyone to follow. This also provides contractual security for the client, as planning certainty is very high.

The disadvantages of Scrum

Because Scrum is only planned in individual Sprints, it is not possible to plan a more precise schedule and to know what the costs will be. The individual Sprints can also lead to losing sight of the big picture and focusing too much on individual tasks. Regular meetings can also lead to a backlog of tasks. Sometimes it is also an advantage to have a supervisor who defines clear responsibilities. As Scrum focuses on the self-organised team, there can be uncertainty in the team.

The disadvantages of the Waterfall model

Because the approach is fixed from the start and cannot be changed, the project lacks flexibility, which can allow errors to creep in that are not identified until the end of the project. This can prolong the project and increase costs. Since the client is not presented with an interim product in the meantime, the surprise at the end can also be negative, or changes must be communicated as early as possible to avoid driving up costs. Another problem with the Waterfall model is that strict separation of the phases is not always achievable.

Implementing Scrum or Waterfall: Tips for Success

Especially if project management is new in the company or the company wants to go new ways, it is helpful to follow a guideline that facilitates the introduction of the Scrum Framework or the Waterfall model in the company.

Tips for the successful implementation of Scrum

Firstly, it is necessary to determine if the project can be executed using Scrum, taking into consideration any legal or contractual limitations and identifying the stakeholders who may influence the project. The next step is to assemble the team, ensuring that they work effectively together, are capable of independent work and efficient project organisation. It is recommended that the team has a variety of knowledge and experience, and that the development team should not exceed eight people to avoid complications in organisation.
At the outset of the project, the Product Backlog should be established and managed by the Product Owner. This list contains all the requirements for the project, sorted by order of importance, and includes all the Product Backlog Items needed to complete the final product. Sprints are planned according to the prioritised list, and a Sprint Backlog is created with the most important tasks for the Sprint, which can be adjusted during implementation. Daily Scrum Meetings are conducted to monitor the project and make any necessary adjustments. The Sprint Retrospective is also important to assess the success of the Sprint and identify any changes that need to be made for the next Sprint.

Tips for the successful implementation of the Waterfall model

Again, it is important to consider whether this model is suitable for the project. Ideally, the project should not take too long, so that any errors do not linger and drive up costs and time. If errors are only discovered at the end of the project, this can have serious consequences. 
It is also beneficial if the project manager or team has experience in the area of the project and can complement each other to minimise the likelihood of mistakes being made in the first place. Depending on the phase, it may be necessary for the team to include other members. Depending on the phase, there may be different tasks that need to be solved by people with different skills. 
An analysis of the stakeholders, the environment, the requirements and the risks should be carried out at the beginning of the project so that the results can be used for the maximum benefit of the project. Stakeholders have a major influence on the project and should be identified from the outset. This will help to determine the right way to deal with them, e.g., in communication.


Both options have their advantages and disadvantages, but a project can benefit from both. In the meantime, there are also more and more projects in which hybrid approaches are pursued. This means taking parts of the classic model, such as the Waterfall model, and adding elements of agile project management, such as Scrum. In this way, you can structure the project clearly from the outset and plan a rough schedule for its completion, but the agile variant also ensures that you can react flexibly to changes in the course of the project by holding daily meetings or running Sprints within one or the other phase.

Scrum vs. Waterfall - the IAPM logo
Author: IAPM internal
Keywords: Project management, Scrum, Waterfall

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