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Iterative Development vs Agile Development

Agile Methodology has become one of the most implemented methodologies in many sectors of industries such as aerospace, construction, architecture, banking, and finances, etc. As companies have started understanding the Agile Methodologies and all the benefits it offers, most of them have already implemented the Agile Methodology or are planning to adopt it. Agile Methodology addresses the drawbacks that were initially faced by using the traditional development methodologies. However, many individuals and organizations are not fully aware of Agile Methodology and often confused with iterative development. Understanding the difference between Agile development and iterative development is one of the main factors for any professional who chooses to work with an Agile organization. Iterative development and Agile development are two different concepts and individuals often confuse one with another. Let us understand in detail the differences between iterative development and Agile development. 

What is Iterative Development?

Iterative development is a type of software development process that makes progress through successive refinement through Product Increments. The Development Team creates the product although knowing that many parts are not completed. The team works on the parts that are not completed and enhances the product till the product is finished and satisfactory. After each iteration, the customer’s feedback is taken into consideration and the software is improved as they add more details to the product. Taking an example of building a search function for a website, at first, the website would contain basic search criteria which could be later enhanced by adding more options in the next iteration. In iterative processes, the developer first makes a minimally viable product, and later uses customer feedback to enhance the product, and continues the process through multiple iterations till the customer is satisfied.

The iterative development process is often used synonymously with Agile development. However, one has to know that even traditional project methodologies can utilize iterative development without using any other components of Agile. When traditional project methodologies use the iterative development method, they take the sequential approach to process further product development. The requirements of the project are determined when the project is started and are constantly developed and tested by the team. Once the development process is completed, and testing is completed, they are repeated based on the feedback of the customers throughout the project till the customer is satisfied. There are gaps given for the team members to rework and improve, however, the customers cannot add the items of requirements, only the development and testing is done repeatedly without overlapping. The timeframes are not specifically considered in an iterative process as it can last up to days, weeks, or even months; there is no real limit. The project is completed only when all the iterations are completed. In iterative development, customers are involved in the initial phase of the product, but they don’t follow up during the project. The requirements are established at the beginning, and the product is provided once for all after its completion. 

What is Agile Development?

Agile development refers to the approach where the product’s value is delivered continuously which is called the product lifecycle approach. It is contrary to the project approach where the product is developed from the beginning till the end. In Agile development, each Product Increment is considered as a single stage in the product’s ongoing evolution. It is one of the most popular approaches that is used in software development. Agile development is considered as the combination of incremental and iterative work sequences that concentrate on customer satisfaction and process adaptability by delivering the working product rapidly. In contrast to the traditional waterfall model where the steps of the development cycle were done sequentially after the last step in a linear manner, Agile development encourages the technique where many phases may overlap. To understand the difference between Agile and iterative development, one has to understand the concept of both iterative and incremental development in Agile. As we have already understood the concept of iterative development, let us know about the incremental process. 

Incremental Process

The process of increments employs the method of delivering the components of the software in various divisions. In this process, every Product Increment is a complete subset of the functionality and is fully coded and tested. Let us take an example of an online food delivery website where the payment could only be done by credit or debit cards. In their next releases, the payments through wallets could also be supported. In this method, the developer already has an idea about the expectations from the customer and builds the Product Increments in several parts such as User Stories. In simple words, incremental development implies that developers continuously integrate various parts of the software project instead of a monolithic approach where developers assemble different parts of the software in one or a few milestones of the project. Hence, the team members roadmap their features and implement them one by one.

How is the Incremental process different from the Iterative Process?

Let us consider an example of an e-learning app to better understand the difference between the incremental and iterative process. Features such as videos, test series, course, student profile management, etc could be considered in this scenario. If the app is built using the iterative part, then the developers built a little of all the features of the app. And will revisit and enhance each part. However, if it is built using an incremental method, then the developers may decide to finish the video part first, then later add the test series, then finally the profile management capabilities. Each part is made perfect before the team decides to move on to the next part.

Agile vs Iterative Methods

Iterative development is not a type of project methodology such as Agile Methodology; it is an approach that could be applied to project methodologies. The main focus of this method is to make the project timeline cyclical to look for necessary improvements and rework. The iterative method acknowledges that rework is typically required and there is always room for improvement. Usually, traditional methodologies use an iterative approach where they repeat various aspects of the methodology, and not change it. 

Agile Methodology is not specifically a project methodology, but an idea or approach to managing projects and more aptly products. It serves as an alternative to traditional methodologies and concentrates on reacting to changes that are unpredictable in projects. Agile Methodology mainly focuses on increasing customer engagement by being both iterative and incremental. In Agile Methodology, the developers also change the aspects of the methods and not only repeat them. It is defined by the Agile Manifesto which is a set of statements that recognizes various aspects of the projects over others. This would include the following:

  • Individuals and interactions over processes and tools. 
  • Working software over comprehensive documentation
  • Customer collaboration over contract negotiation
  • Responding to change over following a plan

Hence, the difference between the Iterative vs Agile model is that Iterative development is a technique used on various projects whereas Agile development is a type of methodology or idea that incorporates several techniques and principles used to approach project management. Agile development combines the use of both iterative and incremental methods during the developmental process. Agile is iterative as it plans for the tasks of one iteration that has to be improved upon with subsequent iterations. It is also incremental as it delivers a completed work throughout the project. During the process of development, “iteration” happens when several features build are either iterating to modify, improve, or remove existing functionality, and “increment” happens while adding new functionality. 

Interpreting Agile Development Using Scrum Framework

As we have theoretically understood the difference between iterative and Agile development, it is always best to know more about it by using examples and referencing them with real-world situations. Let us comprehend Agile development using the simplest and most implemented Scrum Framework. Scrum is one of the most popular implementations of Agile Methodology where developers deliver incremental builds to customers in iterative cycles of 2-4 weeks. Scrum teams are cross-functional and self-organizing teams that consist of three roles namely, ScrumMaster, Product Owner, and the Development Team members. In Scrum, the iterative cycles are known as Sprints whose length may vary based on the organization. However, the range of Sprints is usually 2-4 weeks and once an organization decides the duration of the cycle, it does not change if not necessary.

The Scrum Artifacts are tools used during product development using the Scrum framework. These tools are called Product Backlog and Sprint Backlog which contain a list of user stories and epics which are arranged according to their priority. The Product Backlog contains all the stories necessary to be developed and the Sprint Backlog contains the stories that the team plans to develop through a specific Sprint. Sprint starts with Sprint Planning where the top priority User Stories are selected and arranged in the Sprint Backlog. Everyday daily standups are conducted where the team tracks down the amount of work to be done and if there are any impediments during the Sprint. When the Sprint ends, the Sprint Review is conducted to the Product Owner so that they verify that all the acceptance criteria are met. Following this, ScrumMaster also facilitates Sprint Retrospective where the areas of further improvement are discussed. 

Examples of Implementation of Agile Methodology using Scrum Framework

Consider an example of a food-tech company that uses an Agile methodology to function. This company is already into the hospital discovery/listing business which allows users to look for hospital services nearby. These are the features that are in line for the next releases. 

  • Rating and reviews for the hospital
  • Filters for search
  • Online booking for appointments

The User Stories for these features would be described as follows:

  • As a user, I should be able to rate the hospital so that I could share my experience with others who are planning to visit the same place.
  • As a user, I should be able to apply filters in the search such that finding a specific hospital could be easier.
  • As a user, I should be able to book appointments online without physically visiting there.

These epics could further be split into independent, valuable, estimable, small, negotiable, and testable user stories which could be developed and delivered across with multiple iterations.

Rating and Reviews of Hospitals

Reviews and ratings of a place help the company generate trust among users by adding a sense of social validation by telling the users about several aspects of the hospital such as quality of service, several specialties available, quality of care by the doctors and nurses, hygiene, staff behavior, etc. Let’s say that we want to develop the following functionalities in the ratings and review feature of the app:

  • A rating scale of 1 to 5
  • A review description
  • Share reviews on different kinds of social media platforms

Building all of these features with the functionalities in one Sprint or development cycle is not an easy job. Hence, we have to prioritize and deliver the functionalities in parts, incrementally across multiple releases where Agile comes into consideration.

In the first iteration, the first two most crucial parts of the functionality which are the rating on a scale of 1 to 5 and writing the review with 100 words limit could be developed. In the second iteration, it may seem that the team got feedback from the users that a 100 characters limit is very less and they have to enhance the limit for about 200 characters. Also, the team includes a function of adding pictures to increase the genuineness of reviews. In the next iteration, to increase user engagement on social media sites, the feature to share reviews on Facebook can be delivered. Twitter, Whatsapp, Instagram, and other sites can also be added to the list of social media sites where the reviews could be shared on subsequent releases. Also, the reviews could be sorted based on staff behavior, quality of care, number of specialties in the hospital, etc.

As we have understood how subsequent releases could be added iteratively and incrementally to ratings and reviews, a similar method could also be used for booking online appointments and having filters for search. Developing and delivering Product Increments in Sprints would have many benefits as it allows the developers to get feedback from the users and correct them in the next Sprint. Also, the team does not have to finish the project to release it in the market as it would have been in the traditional software methodologies. Many releases could also be added along the way by understanding the current market trends and growing along with the original roadmap of the project. 

Conclusion

Both the methods whether it is iterative or incremental does not prove to be the best methods for product development when used alone. We can agree that all product releases have to be iterative to some degree and also should be incremental to some extent. Hence, when we discuss which one is better we have to agree that Agile development would be a better choice as software could be developed iteratively and released incrementally in various sizes over time. By this, we can understand that iterative development and Agile development should not be used synonymously and there are greater differences between these development methods. 

References

  • https://medium.com/@ashutoshagrawal1010/agile-methodology-incremental-and-iterative-way-of-development-a6614116ae68
  • https://study.com/academy/lesson/agile-vs-iterative-development.html
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