by Kevin Thompson, Ph.D, PMP, CSP
Scrum is a lightweight agile process framework used primarily for managing software development. Scrum is
- lightweight because it has few prescribed elements
- Three roles: Team, Scrum Master (often a Project Manager), Product Owner (often a Product Manager)
- Three meetings: Sprint Planning, Daily Scrum, Retrospective
- Three artifacts: Product Backlog, Sprint Backlog, Burndown chart
- agile because it maximizes responsiveness to changing customer needs
- a process framework because it is not a process, but a collection of practices and concepts around which a process can be built
For those who are not already “doing Scrum,” the key question is not, “How does it work?” but, “What are the benefits?” This question does not have a unique answer, because it depends on who is asking. Benefits to developers, project managers, and salespeople are different.
This article identifies key benefits of Scrum, and the Scrum practices that produce them.
The Benefits of Scrum
Different stakeholders want different things from a software development process.
- Developers want to write code, not documents.
- Quality Assurance engineers want to create test plans that ensure product quality, and have high-quality code to test.
- Project Managers want a process that is easy to plan, execute, and track.
- Product Managers want features implemented quickly, with no bugs.
- Services and Support personnel want to know exactly what is in all product releases, and have a reliable means to satisfy customer requests for bug fixes and enhancements.
- Sales personnel want to know what is “in the pipeline” for future releases.
- Customers want all of their feature requests and bug-fixes done quickly.
- Executives, Program Managers, and PMO personnel want to know exactly what is happening, and what is planned to happen.
- Everyone wants happy customers.
The list seems long, but the key points are few:
- Team satisfaction and productivity are maximized when effort spent on non-deliverable items (e.g., internal documentation) is kept to a minimum.
- Maximizing quality at each stage minimizes re-work at following stages, and maximizes product quality seen by customers.
- Responsiveness is best achieved by fulfilling customer requests quickly.
- Project status and plans should be visible to everyone who has an interest in them.
Thus the best real-world development process devotes as little effort as possible to artifacts the customer doesn’t value, provides relatively bug-free code at the start of testing, delivers all relevant information to everyone who needs it, and fulfills customer requests quickly.
It is no coincidence that Scrum was designed to satisfy these points.
How Scrum Provides its Benefits
The following sections describe how Scrum practices produce the desired benefits.
Team Satisfaction and Productivity
The “team” consists of the development and Quality Assurance engineers who do the hands-on work of creating a high-quality product. Team members generally find their greatest satisfaction when they can do work that is rewarding.
- For developers, this means designing and writing computer software.
- For QA engineers, this means defining the exact criteria for success through the test cases they develop.
- For all team members, this means producing something they are proud of.
Productivity goes hand-in-hand with eliminating unnecessary work. Scrum addresses team satisfaction and productivity by emphasizing work that is valuable (as a deliverable) and rewarding (to the team), and de-emphasizing what is not (non-deliverable artifacts).
In practice, “non-deliverable artifacts” usually consist of internal documentation about product requirements and design, which customers do not see or value. Scrum projects do require some written documentation, but minimize it by relying as much as possible on real-time communication between people. Thus a Product Manager will write brief requirement descriptions (called “Stories”), and elaborate on the details as needed in discussions with team members.
The requirement for effective real-time communication means that one of the following must be true for all team members, Product Managers, and Project Managers (in order of decreasing desirability):
- All are in the same building
- All are in the same city
- All are in time zones that overlap at least four hours per day
- All are willing to spend hours per day outside normal working times (e.g., transoceanic teams).
The last three cases can only be made to work if real-time teleconference and Web-conference capabilities are available on demand.
Teams implement Stories to the requirements, in a very literal sense: An implementation is not complete (a story is not “done”) unless it satisfies the requirements, as defined in the test cases. While test-driven development is not required for Scrum, test cases do define whether the requirements have been met, and no story is complete unless it passes all of its test cases. If bugs arise, developers fix them until the tests succeed.
This practice ensures that each Story implementation is bug-free, with respect to the requirements, at the time of its completion. It does not prevent regression bugs, so additional testing is necessary after all development is frozen. However, the quality of the product going into regression testing is higher than is the case for products going into the final test period for waterfall projects, and high quality ripples through all stages of the process.
Maximizing Responsiveness to Customers
Responsiveness means providing turnaround to customer requests in a manner that is consistent with customer priorities. Since instant turnaround is not possible, the next best thing is to respond quickly to high priorities, and less quickly to low priorities.
The only way to deliver any new feature or bug-fix quickly is to work in short development cycles, which is why the basic unit of Scrum development, the “Sprint,” is typically 2-4 weeks in length. Longer cycles, composed of two or more Sprints, are also common and often referred to as “Releases” (which is not a Scrum term).
Productivity and job satisfaction both require that people are productively employed, not sitting idle, which means that parallel work for team members is the norm. The two strategies for parallelizing work on a set of Stories are
- Parallel work on serial Stories. The whole team collaborates on one Story, until completion, then begins work on the next.
- Parallel work on parallel Stories. Each team member works on a different Story, until completion, then starts on another one.
Since Sprint lengths are “time boxed” (have rigidly-enforced durations), and unexpected problems can occur, it is often not possible to complete all work planned for a Sprint. For this reason, it is critically important that Story development be serialized as much as possible. This allows us to deliver, say, eight of ten planned Stories when only 80% of the expected work can be completed. In contrast, the parallel-Story strategy might produce no completed Stories at all in this case, and deliver zero value to customers.
The need to serialize Story development implies another important Scrum concept: Ranking. The set of Stories planned for a Sprint is called the Sprint Backlog, within which Stories are ranked (sequenced) for implementation. The Product Manager (say) is responsible for ranking the Stories, so that the most important ones are done first. (The Sprint Backlog is a subset of the larger Product Backlog, which contains all un-implemented requirements.)
The combination of short development cycles and ranking of requirements maximizes responsiveness to customer needs.
“Transparency” means that all steps, inputs, and outputs of the development process are visible-but to whom?
In the narrow sense, as typically described in books on Scrum, transparency applies to the internal membership of the team, the Scrum Master, and the Product Owner, as they need to know the status of the project every day. In this case, and for co-located teams, transparency may be provided by posting index cards or sticky notes with the current Story and task status, along with the current burndown chart, in a public location. The Scrum framework essentially guarantees this level of transparency.
(A “burndown chart” is a bar or line chart showing, each day, the amount of this Sprint’s planned work that remains to be done. The ideal progress is indicated by a diagonal line, trending down to zero on the last day, against which the actual state is compared.)
Transparency in the wider sense means that every stakeholder who has a need for project status information has immediate access it. “Status information” includes not only the status of the current Sprint, but the content of past Sprints or Releases, and the Product Backlog. The Scrum framework does not provide a standard practice to meet this need, but it provides excellent an excellent foundation for meeting it.
Transparency for stakeholders and distributed teams can be achieved via agile project-management applications (e.g., Rally or ScrumWorks), to which all team members and stakeholders are given access. These applications store all requirements and task definitions, track work status, and provide sophisticated reports. They enable distributed teams to collaborate, and allow stakeholders to query for the information they need, without adding a burden on the team or Scrum Master.
Scrum is designed to optimize team satisfaction and productivity, product quality, responsiveness to customers, and transparency for stakeholders. The key practices that enable these benefits include de-emphasizing work on non-deliverable items, implementing and finishing each Story in a Sprint Backlog in rank order, working in short Sprints of 2-4 weeks, and making past, present, and future project information available to all stakeholders.