Software Quality Insights

Feb 25 2009   7:39PM GMT

Using EVM in waterfall, agile software projects: Hows, pros and cons

Scmconsulting Ashfaque Ahmed Profile: Scmconsulting


In my work as a project manager, test manager and consultant, I’ve often used the earned value management (EVM) technique to provide status reports during project execution cycle, among other things. In this post, I share some of the things I’ve learned about it, hoping to help people who have found it difficult to use EVM on software development/testing projects.

I’ve found that EVM can a very useful technique for software development and testing projects. EVM shows how the budget, resources and time is being spent on the project and if the project is going in the right direction. It also shows what correction could be needed to bring the project on the right track. Without EVM; project tracking, monitoring, control and reporting is done on an ad hoc basis. Nobody, including the project stakeholders and the project team itself, knows exactly where the project is or where it is heading to; at any given time during execution of the project.

In EVM, the stress is on project baseline. Before the start of the project; a baseline project plan is developed. At this stage all steps, tasks, resources, time duration for execution of each task and budgets are determined. From this baseline, values for budget, time and resources utilized for each project task is compared when the project execution progresses. This comparison provides information as to whether any task is consuming more or less budget, time or resources compared to the corresponding planned baseline values. These values are also compared for the entire project as well. This information helps in tracking and controlling projects.

One challenge with EVM is that it doesn’t work when requirements are not clear or well defined at initial stage of the project. When requirements keep changing during the software development/testing project, you can’t set realistic baseline values. If the baseline values are not realistic, then EVM method can not work.

EVM can be successfully implemented on software development/testing projects. Suppose we are following the waterfall model for the project. In this case, most of the things for the project are fixed in the beginning of the project. That means we have good baseline figures for the project which will not change. In such a case, EVM can be implemented.

Now, let’s talk about EVM and the agile model. Suppose we have realized that a lot of changes will take place in requirements through out the project. Due to changes in requirements, the project plan will also keep changing to incorporate changes required in different phases of the project due to changes in requirements. So we have no option but to follow an agile method for our project; but how can we have a realistic baseline defined for our project? There are two approaches:

  • In one, you have a project where requirements keep coming and are integrated into the base application model; in other words, an incremental integration model.
  • The other model is the incremental iterative model, in which requirements are grouped into separate small sets. Branches in the main application are made, and a new build is made in each of these branches to fulfill these sets of requirements.

In case of incremental iterative model, we can divide all requirements into manageable groups. Then for a set of requirements, we can make a branch of the base application model and develop this branch as per requirements. We can have several branches of the base application model, and each branch will be further developed using a set of requirements. This way, each branch will have a set of requirements for which all phases of the projects will be well defined. No changes in requirements are allowed in this branch until the iteration is complete.

In case of incremental integration model, the additional design is made based on new requirements. Thus the new design and the new code developed in the next release of the software go directly to the main build.

Using these methods, we are freezing the requirements and thus we can make a good baseline for each of these small iterative projects. We can now easily set budget, timelines and resources for each of these smaller projects and each of the tasks associated with these projects. When the project execution for these iterations starts; we can easily track and monitor these projects.

Finally, there’s another situation in which EVM EVM is relatively simple to implement: software projects using commercial-off-the-shelf (COTS) software. Here if customization of the software package is not required or very minimal, then the project team mostly has to deal with tasks like installing different modules of the package, configuring different modules of the package as per requirements, creating data and finally testing the entire implemented system. In such a scenario, software development is minimal and most requirements are not prone to change. This makes EVM implementation on such projects viable.

Summing up, I advise project leaders to check out EVM. In my experience, software projects often fail because of requirement creep. Using EVM will make software projects manageable and reduce the chances of project failure.

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