Planning with Scrum – Why Bending on Cost isn’t a Great Option

A common misconception about Scrum is that teams using it can’t do planning.  In the next few posts, I’ll be demonstrating some techniques that can be used to plan releases for teams using Scrum.

In a previous post, I talked about the options project teams have when a project starts to fail.  In it, I described the three sides of the “Iron Triangle” that can be adjusted when things start slipping.  In this post, I’ll talk about choosing to flex the cost side of the triangle.

What does flexing cost mean?

Being willing to flex on cost can mean several things.  It could be buying some additional tooling, buying new hardware, or setting up new environments.  Those are all things that might help get a project back on task.  However, when most people talk about being flexible on cost what they often mean is adding additional resources, and that is something that rarely helps get a failing software development project back on track.

Other folks have covered that topic much better than I can, so I won’t go into all the gritty details.  A good place to start is the book “The Mythical Man Month” by Frederick P. Brooks Jr, but there is a wealth of information available on the internet dedicated to this topic.

Why do people do this?  What are we hoping to improve by adding resources to a Scrum group?  One word: velocity.

Why doesn’t this work?

Velocity is a tricky beast.  At its simplest, velocity is a measure of how much work a Scrum team can complete during a single sprint.  While the concept of velocity is simple, understanding how it is affected by changes to a team is anything but.  In general, adding new people to a Scrum team tends to initially disrupt the ability of the team to get work done.

From a purely technical perspective, the usefulness of adding resources to tasks relies on that work being parallelizable.  In other words, the work can be broken up into pieces that have no dependencies on each other and can be consolidated into a whole after the pieces are all complete.  Unfortunately, most software development tasks don’t fall into this category, and adding additional resources only adds to confusion and communication problems.

Ignoring technical issues, the people and personality challenges caused by adding “new fish to the pond” can also prevent velocity from immediately improving.  These kinds of factors are also very hard to mitigate and usually just need to run their course.

Can additional cost ever help?

While adding more resources to a Scrum team in the hopes to have an immediate positive impact on velocity doesn’t tend to work, there are ways to increase the team’s velocity in the long run.

Adding members can eventually increase a team’s velocity.  If the need for more capacity is recognized early, adding new members to the group will increase the velocity after the group has had the time to reintegrate.  How long that takes varies from group to group.  These additions to the group would ideally be new permanent members of the team, not simply burst capacity brought in to push schedule to the left.  There is also a “sweet spot” for team size.  If the team grows past about nine people, it may be wise to split the group into more than one Scrum team.

If team members are not fully allocated to the Scrum team, increasing the existing team members’ allocation will absolutely allow them to get more done each Sprint.  My preference would be for folks to be 100% dedicated to their Scrum team, but I also live in the real world and understand that that doesn’t always happen.  If your Scrum team members aren’t 100%, making them full time is the best way to increase their capacity for work.

So how does this help with planning?

It doesn’t, much.  Since it’s really not possible to know what effect adding team members will have on velocity, you can’t really plan accordingly.  Bummer.

Given my druthers, on projects I’m working on, I’d much rather be flexible on schedule or scope than on cost.  I’ll talk about those in future posts.

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