Software Development Industry

Agile vs Waterfall: Which Method is More Successful?

Whether you’re manufacturing a car, engineering a spacecraft, or building a house, project-management methodologies are the backbone of any plan, and just like the projects in these fields, software development also requires a solid project-management approach.

There are a number of different methodologies in the software-development industry – some are new takes on old methods and others have adapted a relatively new approach. The two most commonly used methods in this field are the Agile and traditional Waterfall models.

Most software companies that follow these two models will argue that their chosen method is superior in respects, so before we answer the question, “Which one is more successful?”, we should look at their main differences.

Agile Methodologies

Born in the early 1990s, agile methodologies share a lot of the same qualities as their Gen-Y peers – bold, youthful, ambitious, flexible, and forever seeking new challenges. This model is fast becoming the project-management method of choice, largely due to its focus on optimizing development time and producing an operational application in the shortest time possible.

A common feature of the agile methodologies is sprints – miniature projects within the main project, usually divided up into two- to four-week increments. Each sprint is designed to produce a new working feature and is centered on developing the most essential parts of the application.

This piece-by-piece approach allows developers to foresee and respond to all major obstacles and to set the project on a straighter course of development.

Waterfall Model

Traditionally used in the construction and manufacturing industries, the waterfall model has found its way into software-development projects. Unlike the flexible nature of the agile methodologies, the waterfall model is defined by its strict and linear principles. Projects start at the first phase and only progress to the next when everything in the previous phase has been completed.

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Agile vs Waterfall: Project Success and Failure Rates

A number of different studies have been conducted on the success and IT projects failure rates associated with the agile and waterfall methods across a number of areas, and the results are fairly unanimous:

Ambysoft’s 2013 Project Success Rates Survey concluded that the agile method has a 64% success rate, compared to just 49% for the waterfall model.

IT project success rates

Ambysoft’s survey analyzed the main factors that contribute to a project’s success or failure and found the following:

Why software development projects fail

The 2015 CHAOS report from the Standish Group also discovered that the agile method produces a higher success rate than the waterfall model:

agile vs. waterfall success rate

*Challenged projects are defined as projects that were completed, but went over budget, time, or both.

The results above clearly show that the agile methodologies deliver more successful projects than the waterfall model, but what areas of software development contribute to a project’s success of failure? Well, the truth is that there are many, but here are the three main factors:

The Software-Development Process

The software-development process is made up of a number of stages. Within the agile and waterfall models, the stages are the usually the same, but involve different approaches:

agile vs waterfall software development process

The interconnected development phases in the agile methodologies allow developers and clients to access each part of the application sooner and to make decisions on how the rest of the application should progress. This adds huge benefits to both parties, as the end result contains all the design elements, features, and functions necessary for a working application.

Due to the linear character of the waterfall model, each stage of the development process is started and completed one by one. In theory, this approach should produce a working application sooner; however, building an application isn’t that simple and straightforward. Obstacles are a dime a dozen in software development, and all it takes is one small, undetected bug in the beginning of the process to bring the whole project crashing down.

Application Testing

Quality assurance and testing are just as important to an application’s success as building its codebase. Bugs, performance issues, and security flaws need to be detected and resolved early on and repeatedly throughout the development process to allow the project to advance.

Testing and Q&A are constant features of the agile methodologies. Once a new piece of the application is built, it is put through a series of tests to identify bugs and other non-compliant parts. This ensures the new feature will seamlessly integrate with the rest of the application and provides overall quality.

The testing phase in the waterfall model happens separately, usually after the integration phase. As this is the first time application testing is conducted, it is not unusual for the application to be full of bugs and other major problems. This results in more time spent in the testing phase – or worse, the phase is attempted half-heartedly (or partially completed) due to the pressure applied by the client to move the project forward into the next development stage.

The Client-Developer Relationship

Another key area in developing a successful application is the client and developer relationship. Full cooperation, complete transparency, and strong communication are all vital to an application’s future success. The need for strong collaboration in the agile methodologies encourages the client and developers to work in unison, and provides the client with a greater feeling of engagement and trust.


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