Comparison Of Iterative Vs Incremental Development: A Guide

Updated 27 September 2022

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In the Agile methodology, there are two main software development models, namely the incremental and the iterative approach. When a project team embarks on a new software development venture, they select one of these two approaches for development that considers both the product requirements and the client's expectations. Learning about these approaches can enable you to select the one that best meets your requirements for product development. In this article, we compare iterative vs incremental software development methodologies, discuss what they mean and also elaborate on their differences to assist you in making an informed decision.

Iterative Vs Incremental Development Definitions

Before comparing iterative vs incremental methodologies, it is important to understand what they mean.

What is iterative development?

In the iterative approach, development teams refine an idea as they go through successive sections of the iterative cycle, called sprints. Teams gradually add features and functionalities, but they may not wait to finish them all before releasing them. They first release a rudimentary version of every feature, after which they iteratively develop it based on user input received from the initial release. The feedback enables them to decide what they may eliminate and what they can include in the next edition to enhance the user experience.

For instance, if an e-commerce website is being developed using the iterative model, the development team can first release a very basic version of all necessary functionalities, including search, product information, shopping basket, checkout, wishlist and customer reviews. For the second iterative release, the team can improve some of the current basic capabilities by using analytics and input from stakeholders, consumers or other sources. After that, the team keeps adding new concepts and requirements and eliminates low-value usage regions in each iterative release, subsequently progressively improving the e-commerce website's functionality and performance.

What is incremental development?

In the incremental approach, the software development process comprises small, manageable chunks, known as increments. Each increment builds on the one before it, allowing for gradual improvements. Building on the progress they achieve in each stage, a development team works on each crucial phase of the complete software development life cycle at varying time frames and speeds. At the end of each phase or increment, there is usually nothing to review or give feedback on because the entire solution comprises only parts. Teams cannot produce the finished result until the last phase of the incremental process.

For instance, say an e-commerce website is being developed using the incremental model. The end product may include a search option, product details, shopping basket, checkout, favourite items and client testimonials. For the first released increment, the team creates the fundamental features required to make a purchase, such as product information, search, shopping cart and checkout. The second released increment grows on this fundamental functionality and may include new features like favourites. Following that, the third released increment might include user reviews or other relevant features. They do not make the increments available until they are all complete.

Comparison Of Iterative Vs Incremental Development

You can consider the following factors to find out the difference between these two developmental approaches:

Approach

The iterative method divides the process into separate, fully operational development cycles or sprints to accomplish its goals. This enables the project team to create a finished product before testing a later, enhanced version of it. The incremental approach, in contrast, involves developing the entire product in small, incomplete chunks or increments, with a fully working version only available at the conclusion of the development process when the development team assembles all components together to produce the final product.

Stages

An ongoing cycle of planning, analysis, design, implementation, testing and evaluation is a part of the iterative process. Each cycle results in a development phase that serves as the foundation for the following cycle of iterative improvement, which includes the same steps. Similarly, the stages of the incremental approach typically include design, functional requirements, execution and testing. Every time the team releases a new version of a system, they enhance its functionality. They continue doing this until they implement all the required functions or features.

Error detection

As each iteration in the iterative technique represents a fully independent variant, the team may find errors faster. With this, you may examine the entire development process to find faults before going on to the next iteration. When using an incremental framework, though, each component of the project may be complete but is not usable by itself. Because of this, the team cannot discover any defects, errors or other problems until the finishing of the project and the assembling of the product is complete.

Change implementation

The iterative approach encourages introducing periodic changes because the development team can easily add fresh modifications to the product throughout the following iteration cycle. The incremental approach, in comparison, is more strict because there are rarely any changes to implement until the very last stage of the product development process. Changes often occur after the start of the quality control testing and customer evaluation phases.

Risk aversion

Because the project team can evaluate the product at each iteration, the iterative approach is more suited for lowering risk. By doing this, they can be sure to make the necessary adjustments to address past problems before moving on to the final version. Whereas, the incremental approach can be riskier because it can take longer to finish a product and the team cannot test it until the very end of the cycle.

User engagement

The iterative process places more focus on user engagement because users get to try out every version of the product. Through this evaluation, the development team is able to get constructive criticism that may help improve the end-user experience. The incremental approach, in comparison, results in lower user involvement because customers usually wait until the very end of the development process before they can test the product.

Time

Fast-moving sprints, used in the iterative technique to complete each cycle, allow you to produce a product quickly and assess its final composition for essential functional capabilities and features. The incremental method, in comparison, often requires more time to finish a product. This is so because each component you work on is merely one stage in the development of the final product. The iterative approach may help save time through efficient resource utilisation.

Quality of product

In the iterative method, the development team is likely to create a number of low-quality or unrefined versions of their product because the iterative process concentrates on making quick variants one after another. This can get better over time until they perfect the method for producing a high-quality item. Comparatively, an incremental process team is likely to deliver a higher quality product after just one cycle because they are putting all of their attention into developing a single enhanced version.

Expense

The iterative technique can become more expensive over time, even though it may not be a problem at first, especially if the development team requires increasing their budget and resources consistently to finance several iterations until they find the ideal development method. The incremental approach is typically more economical because the project team only requires using their budget for one iteration and any subsequent budget outlays are for changes or alterations.

Adaptability

The iterative approach can be more suitable for managing unforeseen circumstances because a project team may adjust to the new circumstances at the next iteration. The incremental approach, on the contrary, may not be as successful at accepting change because it adheres to a specific procedure from beginning to end. Any modifications to this method risk delaying the entire development cycle.

Benefits

The iterative model provides early feedback and is often easier to manage. It offers functional software right away and adds value to the business with each iteration. The iterative approach can make adjustments in each iteration and successfully manage risks as it is responsive to changes in requirements during development. It can also be useful for clients who require something to experiment with while determining their requirements.

When changing scope and requirements, the incremental method is less expensive and more flexible. As various teams can work on numerous modules simultaneously and finish them at various periods, parallel development is possible. This method allows for the separation of concerns, as each module is a standalone portion of the product. The ability to add or remove modules from the product allows it to adapt to changes in scope. Each module can identify and address risks as well.

Suitability

Whether you choose an incremental or an iterative development approach depends on the kind of product you want to build and the requirements of your team. Utilising an incremental process can be the best option if you want a product that is likely to be of greater quality and cost less to produce. Similarly, you might get more satisfaction in the iterative process if your priorities are quick delivery and regular client interaction.