The Pros and Cons of Agile and Waterfall
Agile and Waterfall(1)are potentiallytwo very different ways of delivering projects. Firstly we will describe them both and then compare their respective advantages and disadvantages.
Waterfall (V) Model:
Waterfall (1) projects go through a number of sequential or overlapping phases. This defines the life cycle of the development effort of the project. The principal difference with Agile is that in Waterfall, requirements are defined near the start of the project. Then they may be subject to change control through all the following phases.
Waterfall was adapted from Engineering. On large-scale physical projects, design is often a critical activity and the impact (on cost and schedule) of changing the design downstream can be very significant.
Somepeoplestate incorrectly that in Waterfallif an error is found in the later stagesof a project, it will need to be scrapped and started again. While this is not impossible, itwould have to be a very significant issue to cause this level of impact. In truth, this will only occur ifthere is very poor control of a project.
It is also not true that Waterfall projects never involve iteration or feedback. They certainly can but some project teams choose not to.
Agile itself is not a PM frameworkand it is not a “methodology”. It is a set of principles and values relating to product development, specifically producingsoftware (2). There are, however, methods based on Agile principles, and these are Product Development methods, not project management frameworks.
The biggest difference between Agile and Waterfall is that typically in Agile the deliverable is produced and accepted incrementally, around short iterations or equivalent (usually 2-4 weeks). Additionally, using Agile, requirements are normally defined around each iteration, rather than at the start of the project in a single requirements phase.
Prior to this, higher-level items such as features will usually be identified. These will then be broken down into discrete items to be fully defined and developed within iterations.
One key aim of Agile isto try to retain as much flexibility as possible throughout the development cycle.
Certain types of projects will never suit a truly Agile approach. For example, if the main project deliverable cannot be defined, produced (and accepted) sequentially and incrementally, it is unlikely that the core of Agile can be used.
However, any project can benefit from some of the practices commonly found in Agile, notably communication.
Clearly, the two approachesare very different and will have completelydifferent pros and cons.
Solet’s look first atAgile:
|Agile promotes some of the best practices found in development environments. Some of the risk in a project should be reduced as the output of developers is reviewed early and constantly during development.||Agile is simple to understand in principle but hard to do well in practice. It requires real commitment and first attempts are not likely to go very well.|
|When projects are genuinely new they usually require creativity. Requirements can then emerge as understanding matures and grows.||It is less predictable what will be delivered at the end.|
|Flexibility can be higher than traditional methods - although this is not guaranteed. Changes (e.g. in prioritisation) can be introduced at almost any stage.||Agile requires high levels of collaboration and very regular communication between developers and users (e.g. Product Owner). This is always desirable but may not always be feasible and requires continual commitment and time from the business and developers.|
|Agile encourages or requires frequent communication between developers and those who will ultimately accept and use the deliverable. This should pay major dividends when effective. For example, feedback can be incorporated into future iterations as increments are delivered and reviewed by users or a Product Owner or both. False assumptions made by developers can be recognised very early reducing impact. Agile gives us continual opportunities to learn via this feedback.||Agile is very intensive for both developers and users. There can be reasons that may prevent this for example if developers work on multiple projects at one time.|
The only downside to the opportunities to learn is that people have got to be prepared to.
|It should reduce the 'silos' that too often exist within project 'teams' - something that always damages projects (as it should result in a collaborative style of working).||There can be less of a blueprint of what the final deliverable will be. This can make it harder to gain commitment to the project by stakeholders at the early stage.|
|It should result in far less re-work on projects as issues and changes should be picked up much earlier.||Agile can be challenging when there is a supplier-customer relationship. Customers typically want to know what they are getting for their money as early as possible. It can be far harder to estimate timescales and costs as there is less 'definition' to base estimates on.|
|Collaboration is usually much higher with Agile. Although not guaranteed, this can result in more successful development environments, in terms of product quality (i.e. fit for purpose).||Agile can be very challenging on much larger projects or where co-location is not possible (between developers and the business).|
|With the common use of visuals, (boards, charts, Kanban etc) it can be easy to see what is going on (literally) what is done and what is yet to do, assuming the visuals are well organised, presented and up-to-date. This in itself can be a major benefit.||In Agile there can be a great reluctance (by some) to adopt or accept deadlines. Projects don't exist in isolation so when this happens it can be a real issue. Agile methods typically only address the product development and large-scale projects can be made up of many other elements. |
Other obvious examples where Agile methods are not typically strong: dealing with lead times and major dependencies.
|On well managed projects Waterfall may provide more confidence of what will finally be delivered earlier in the life-cycle.||Many organisations and people really don't find defining requirements (up front) easy to do - especially early in some types of projects. The assumptions upon which early stage plans are based may be very flawed and too often are taken as being based on certainty.|
|Project team members don't need to be co-located although the risks associated with this must be managed carefully.||Communication can be a far higher risk - especially when there is limited early review of outputs and deliverables or when one-way methods of communication are used to convey requirements.|
|Where large-scale design or analysis is required, or the impact of downstream changes to design is very high, this is likely to be a far more suitable approach.||Risk in general can be far higher with Waterfall, for example as the scope for invalid assumptions is unlimited. If you add this to the high cost of making changes later in a Waterfall project, it is easy to see why some are very expensive, over budget and late. Too often, assurance of products being fit-for-purpose is demonstrated very late in Waterfall projects.|
|Where there are many interfaces and dependencies outside of the basic product development, waterfall projects tend to have the tools to model and manage these.||Waterfall projects don't have to be but tend to be made up of 'teams within teams'. This can be a major disadvantage to any project.|
Summary and Conclusions:
Agile and Waterfall are very different and it will not always be possible to choose between them both. Waterfall could be applied to virtually any type of (IT) project. Agile requires specificconditions to be in place to be possible but isnot applicable to certain projects – especially those of a large physical nature. Most of the conditions for Agile to be possible relate to the working environment and practices that can/cannot be employed by the whole project team. Not just those responsible for product development. There also needs to be flexibility around requirements together with the capacity to deliver and accept products incrementally.
1 – The term “waterfall” is used liberally and many would say incorrectly to describe all non-iterative (i.e. predictive) forms of project management frameworks. Waterfall, as defined in 1976, is a (rarely used) software development framework. However, the central principles of Waterfall (i.e. sequential/overlapping phases) were borrowed from Engineering. Therefore there is a clear parallel between IT development methods that follow a Waterfall type of approach and many physical and engineering projects, which still do to this day and will continue to do for a long time to come, due to the physical nature of those projects, meaning some things have to be done in sequence.
2 – We say “mainly software” as there are few types of projects outside of the software domain where the deliverable can truly be produced and accepted sequentially and incrementally or where requirements can evolve within the development phase. A phased delivery of any project does not mean it is Agile (despite some claims that it is). It is simply a phased delivery.
Agile projects are typically cheaper and can be delivered quickly. They offer greater flexibility, but also produce less predictable results due to the uncertainty and unclear nature of many of the project characteristics. Waterfall projects are typically more expensive and take longer to deliver.What is the main difference between Agile and Waterfall? ›
The main difference is that Waterfall is a linear system of working that requires the team to complete each project phase before moving on to the next one while Agile encourages the team to work simultaneously on different phases of the project.Can you tell me the difference between Waterfall and Agile in what kind of project should one be applied and not the other? ›
Agile and Waterfall are two popular methods for organizing projects. Waterfall is a more traditional approach to project management, involving a linear flow. Agile, on the other hand, embraces an iterative process. Waterfall is best for projects with concrete timelines and well-defined deliverables.What are the pros and cons of Agile? ›
|More flexible||Hard to predict|
|Product get to market faster||Final product is not released first|
|Better communication||Documentation gets left behind|
- Pro: Everyone gets up to speed quickly. ...
- Pro: Timescales are kept. ...
- Pro: No financial surprises. ...
- Pro: Testing is made easy. ...
- Pro: The outcome is crystal clear. ...
- Pro: Deal with issues in the design. ...
- Pro: What you plan is what you get. ...
- Con: Needs can be difficult to define.
In waterfall testing, testing is a separate phase. In agile testing, testing is performed alongside the development. In waterfall testing, testing is carried out only after the completion of development. In agile testing, development team and testing team work together.Which is best Agile or Waterfall? ›
If the project timeline is fixed and can not be moved, Waterfall will offer a more predictable outcome. If you need to get the project delivered in a short amount of time, Agile is the appropriate choice here where action and getting things built is more important than documentation and process.What are the disadvantages of Agile? ›
- Poor resource planning. ...
- Limited documentation. ...
- Fragmented output. ...
- No finite end. ...
- Difficult measurement.
Once a step has been completed in Waterfall, it's difficult to go back and make changes. In contrast, Agile builds a working version of the whole project (an MVP) so the customer can shape how it's built.
An Agile methodology is a superior choice when the client is uncertain about requirements or wants to be closely involved in the development process, and if timelines are short and they want rapid delivery. Waterfall is superior if there are complex dependencies, but Agile is preferable when dependencies are minimal.
Agile methods can help teams manage work more efficiently and do the work more effectively while delivering the highest quality product within the constraints of the budget.What are 3 advantages to Agile methods? ›
Agile produces important metrics like lead time, cycle time, and throughput that helps measure the team's performance, identify bottlenecks and make data-driven decisions to correct them. The Agile framework is a powerful tool that helps managers, team members, and clients.What are the disadvantages of waterfall model? ›
Waterfall Model - Disadvantages
No working software is produced until late during the life cycle. High amounts of risk and uncertainty. Not a good model for complex and object-oriented projects. Poor model for long and ongoing projects.
Disadvantages of the waterfall method
The client's limited visibility throughout the project might result in the deliverables not meeting their expectations. Changes can be difficult and costly to implement and the team needs to review the entire project from the beginning, considering that phases are interconnected.
Both the models, Waterfall model and Spiral model are used in software development. Waterfall model is also known as classical or linear model because it follows sequential stages while the spiral model does not follow the sequential stages it follows the evolutionary way.Is Agile more flexible than Waterfall? ›
It's clear that agile is more flexible, and waterfall is more rigid. Each methodology has its pros and cons, meaning these methodologies are better suited for different project types.Which Agile is best? ›
Agile Best Practices: Kanban Project Management
- Visualizing Workflows. ...
- Limiting Work in Progress. ...
- Continuous Feedback. ...
- Focusing on Flow.
The 3 principles behind agile tools - Transparency, Iteration, Empowerment.What are the disadvantages of Waterfall to Agile? ›
- The process is not as flexible as agile approaches.
- It's difficult to foresee roadblocks and dependencies that could delay work.
- Work is not always evenly spread out across the team.
- Project overload is possible.
- Short-lived teams may ignore conflict for the sake of getting to the end of the project.
The fundamental problem with agile, as many companies use it, is that its relentless pace biases developers. They want to get out a minimum viable product in only a few weeks, so they skimp on scoping out just what the product should accomplish.
Now that you've grasped the several sectors in which the waterfall model used to be and is still deployed, here is a real-life example of the waterfall model at work. Here, the waterfall model is used to manufacture a tractor, with each of its phases outlining the work that needs to be done.Can a project be both Agile and waterfall? ›
The Agile-Waterfall Hybrid is often considered a smart approach for adopting both methodologies without compromising too much, essentially utilizing the best of both worlds.Why Agile is used? ›
The approach prioritizes quick delivery, adapting to change, and collaboration rather than top-down management and following a set plan. In Agile processes, there is constant feedback, allowing team members to adjust to challenges as they arise and stakeholders an opportunity to communicate consistently.What are the top 5 Agile principles? ›
There are 5 main Agile methodologies: Scrum, Kanban, Extreme Programming (XP), Lean Development e Crystal.Why Agile is faster? ›
The real reason why agile is able to deliver the product faster to market is that it implicitly applies the 80/20 rule, where product owner prioritizes the features to be implemented first, based on their values (ROI) to the end product.What is the most important thing in Agile? ›
An Agile focus should be on improving the product and advancing consistently. Simplicity — the art of maximizing the amount of work not done — is essential. The goal is to get just enough done to complete the requested project.What are the 2 benefits of applying Agile? ›
The benefits of the agile method are cutting costs and time to market in half, while increasing application quality and customer satisfaction.What are 3 benefits to using the waterfall model? ›
Advantages of waterfall model
This model is simple and easy to understand and use. It is easy to manage due to the rigidity of the model – each phase has specific deliverables and a review process. In this model phases are processed and completed one at a time. Phases do not overlap.
If the project timeline is fixed and can not be moved, Waterfall will offer a more predictable outcome. If you need to get the project delivered in a short amount of time, Agile is the appropriate choice here where action and getting things built is more important than documentation and process.What is the cons of Waterfall? ›
Disadvantages of waterfall
Unlike agile, this methodology does not allow for discovery, iteration, and refinement whilst developing the product. Instead, new requirements must be written.
There is plenty of supporting evidence that Agile wins out over Waterfall Projects. That data comes from 25 years of studying project success and failure rates is pretty clear. Agile projects are 2X more likely to succeed and less than half as likely to fail than Waterfall.Why Agile is faster than waterfall? ›
Agile sees the customer as part of the implementation team and includes them at each part of the process. In contrast, Waterfall tends to spend a lot of time with the customer at the start, trying to document all the perceived requirements. But once this has happened, the implementation team usually take over.Why is Agile better? ›
Agile teams are known to be highly efficient at getting work done. Because Agile teams share a collaborative culture, efficiencies tend to have a ripple effect. Look for an Agile solutions provides insights into delivery trends to remove bottlenecks and adapt workflow processes for improved productivity.What are the benefits of Agile? ›
- Increased visibility.
- Increased adaptability (agility)
- Increased alignment.
- Increased product quality.
- Increased business value.
- Increased customer satisfaction.
- Decreased risk.
The disadvantage of waterfall development is that it does not allow much reflection or revision. Once an application is in the testing stage, it is very difficult to go back and change something that was not well-documented or thought upon in the concept stage.Why waterfall model is best? ›
The advantages of the waterfall methodology are that: Requirements are completed early in the project, enabling the team to define the entire project scope, create a complete schedule, and design the overall application.Why is waterfall high risk? ›
The greatest disadvantage of Waterfall is the inability to return to previous stages of work when they have already been finished. Many Waterfall teams have to run their projects from the very beginning because of this fact. The range of customer involvement in Waterfall projects is very low.How do you decide between Agile and waterfall? ›
An Agile methodology is a superior choice when the client is uncertain about requirements or wants to be closely involved in the development process, and if timelines are short and they want rapid delivery. Waterfall is superior if there are complex dependencies, but Agile is preferable when dependencies are minimal.Is Agile more flexible than waterfall? ›
It's clear that agile is more flexible, and waterfall is more rigid. Each methodology has its pros and cons, meaning these methodologies are better suited for different project types.Why is Agile better than waterfall medium? ›
Agile can accommodate new, evolving requirements any time during the project, whereas it is not possible Waterfall to go back to a completed phase and make changes.