Seven Options for Handling Interruptions in Scrum and Other ‎Agile Methods

In both my consulting and my teaching practices I am astonished by how many people ask about ‎handling interruptions to the work of an Agile team. Of course, many organizations are interrupt-‎driven, particularly with shoddy software in the field (and by shoddy, I don’t just mean full of bugs but ‎also having very poor usability). Interruptions also come for positive reasons such as a changing ‎marketplace. Since this is such a common problem, I thought that I should write an article which I feel ‎is mostly just stating the obvious. Apparently “the obvious” is popular!‎

Option One: Follow Scrum Strictly – no interruptions!

The rules of Scrum are clear: if it isn’t part of the team’s work for a Sprint, then it shouldn’t be done.  From the moment the team commits to work in Sprint Planning to the end of the Sprint with the Sprint Review, the team needs to be protected from interruptions.  If an interruption is truly urgent enough to warrant the team’s attention mid-Sprint, then the Sprint can be canceled.  This is a pretty extreme result however since it invalidates the team’s previous commitment.

The Scrum approach is based on the basic philosophy that Scrum is a system to expose the problems and obstacles in the organization.  This is painful!  In the case of interruptions, Scrum then is metaphorically throwing them back in the face of the organization and saying “this is bad behavior!  Fix the behavior that causes so many interruptions, don’t find a way to accommodate interruptions.”

For example, many teams are faced with interruptions related to their support of the software they are creating.  In Scrum, deflecting the interruptions forces the team and the organization to examine the root causes of the support issues and fix them.  If the team is producing software with lots of defects, then that needs to change.  If the team is producing software that is hard to use, then that needs to change.  If the team is producing software without the appropriate level of user documentation, then that needs to change.  But what doesn’t change is the team breaking the safety of the Sprint defined by the rules of Scrum.

Option Two: Allocate a Portion of Time to Interruptions

Given certain conditions, the amount of interruption of a team can be “stable”. If this is the case, then the team can reasonably set aside a certain percentage of their time to handle interruptions. Determining if this is possible can be done by tracking the occurrence of interruptions and the level of effort to handle them.

In a team using this method, there are two ways to allocate this time: everyone on the team gives a certain amount of time each day to handling interruptions OR one or two people on the team are committed full-time for a cycle to handling interruptions. In either case, if the amount of actual time spent on interruptions is less than the amount of time available, then that difference of time must be used carefully. Generally, the best use of this extra time is to work on resolving the root causes of interruptions. For example, if one person of a team is dedicated to dealing with interruptions, and most interruptions come from in-the-field bug support requests, then that person might spend any extra time working on fixing older lower-severity defects.

The amount of time that the team is allocated to handling interruptions should never be exceeded otherwise the team’s commitments at the start of the cycle are not really commitments.

This option is by far the most common systematic approach to dealing with defects

Option Three: Visible Negotiation of Change

Another common method of handling interruptions is the “fluorescent note card” method which requires visible stakeholder negotiation around the impact of interruptions. With this method, any time a stakeholder comes to the team with an interruption request, the ScrumMaster/Coach/Process Facilitator writes the request on a bright colored note card so that it is easy to distinguish it from the other tasks the team is working on in their current cycle.   The ScrumMaster then asks the team to do a task breakdown on the card and using their normal process (whatever that is) estimates the work effort. The requesting stakeholder then has to negotiate with any other stakeholders (and in particular the Product Owner/Growth Facilitator about what work to remove from the iteration in order to make room for the new work. This process works well primarily because it makes the tradeoffs visible. It does not work so well with letting the team make and keep their commitments which can have a long-term impact on trust.

This approach requires a few things to be in place to be effective:

1. A visible task board instead of electronic tools for task tracking.  The visibility makes the change much more immediate and you must have the stakeholders involved right in the same physical space.  An electronic tool makes this too abstract and can lead to some important stakeholders not being properly aware of changes.
2. A team that is reasonably good at estimating.  By “good” I mean both accurate and fast.  If it takes the team half an hour to do an accurate estimate, then that is already a significant interruption in itself!  A team should be able to look at an interruption, break down the tasks and come up with a reasonably accurate estimate within no more than 10 minutes.  Remember that doing this is already task switching so there is going to be an additional cost to the team.
3. Finally, and perhaps most importantly, a clear agreement must be in place among stakeholders that this approach to interruptions is allowed and that the consequence of it is that the team cannot be held accountable for their commitments!!!  I cannot stress this enough!

Option Four: Separate Team for Interruptions

This option is fairly self-explanatory and in fact is just a way of saying that you have a separate support group who deals with interruptions.  The more technically capable this group is, and the more authority they have to make changes to the code/database/etc., the more effective they will be at protecting the agile teams from interruptions.

In some ways, this is a good approach because it makes the cost of interruptions very visible to the business: how much does your support team cost?  If this cost is growing, then it means that the development teams are creating software that is harder and harder to support.

If you follow this approach, please ensure that you do not rotate development team members through the support team as this damages the team-building process for both the development team and the support team.

(One radical option to try as an add-on to this is to defray the cost of this support team by tying developer’s salaries to the cost of support.  To make this palatable, you might simply say to the development team that any time a support person can be laid off due to improved quality in the product/system, that person’s salary will be permanently distributed and added as a raise to the salaries of the development folks.  PS.  I’ve never seen any organization do this – it’s just a theory.)

Option Five: Extremely Short Cycles

A less common, but interesting method for handling interruptions is to have extremely short iterations. In this method, choose your iteration length to be so short that you can always start work on urgent interruptions before anyone gets impatient! This can be exhausting, but it is one of the best ways to get the team and the organization to understand the large toll that these interruptions take.

There is a simple way to determine how long your cycle should be based on measurement.  Choose a “normal” duration (e.g. one or two weeks) and for several cycles track how many interruptions are submitted to the team, and how urgent is the turn-around time on those interruptions.  After several cycles, the team can then adjust its cycle length so that, on average, the team is able to start and finish a cycle in a time shorter than the expected frequency of interruptions.

For example, one team I worked with found that in general, they were getting interruptions that needed to be handled within three or four days, but more urgent interruptions were rare.  They decided to use a cycle that was only two days long so that on average they would complete handling an interruption in three days.  (Interruption comes half way through a cycle and is put on the backlog at the top.  The next cycle they start and finish the interruption.  Elapsed time is three days.)

Option Six: Status Quo / Suffering

There is nothing inherently wrong with continuing with your current approach to handling interruptions.  It probably makes some people miserable, but there are also some people who really enjoy crisis and constant change.  In fact, it may be part of the culture of your organization or something that is strategically important in your particular industry.  That doesn’t mean you can’t be agile, but it may mean that you are making compromises where you are trading off team performance for some other benefit.  it is important that if you choose to continue with your status quo, that you make the trade-off transparent.  Tell everyone on your teams exactly why you are making the trade-off and what is the expected benefit of doing so.

Option Seven: Commitment Velocity

The most sophisticated option is based on measuring a special kind of velocity called “Commitment Velocity”.  This is a mechanism that allows both interruptions to be handled mid-cycle and for teams to make commitments that they can keep.  In the simplest terms, Commitment Velocity is the minimum historical slope of a team’s Sprint burndown.

For example, if a team in Sprint 1 has 240 units of effort at the start of the Sprint, but, partly due to interruptions, does not finish and then has 40 units of effort left unfinished at the end of the Sprint, then the Commitment Velocity (slope) of the team is 240 – 40 = 200.  In their next Sprint planning meeting, they would plan such that they had at most 200 unites of effort in their Sprint plan.  The team then does their second Sprint and again, partly due to interruptions, they don’t finish everything.  Perhaps this second sprint started with 195 units of effort (<200) and finished with 10 units of effort remaining.  Their new Commitment Velocity is 195 – 10 = 185.  They do a third sprint, but they finish everything.

It is tempting for the team to perhaps take an average – maybe they finished 200 units of effort in their third Sprint so they average 200, 185 and 200 leaving 195.  This is not Commitment Velocity.  By definition, an average means that the team will successfully complete all their work 50% of the time.

Instead, the team maintains its Commitment Velocity of 185 for their fourth Sprint.  By the law of large numbers and the central limit theorem, as the team uses this tool of Commitment Velocity for more and more Sprints, eventually their ability to keep their commitments, even with interruptions) will become closer and closer to 100% certain.

Selecting an Option

Ultimately, the most important thing in selecting one of these options is to do so consciously and in the spirit of learning that underlies agile methods.  Choose  an option and then stick with it long enough to truly understand if it is working for you or not.

There are some things to consider as well:

• If you are trying to do a dramatic improvement in how your organization gets stuff done, I would recommend choosing either Option One (Follow Scrum Strictly) or Option Seven (Commitment Velocity).  Both of these are options that put pressure on the team and the organization to improve.
• If you don’t have strong executive support for Agile, then probably Options Two (Time Allocation), Four (Separate Team) and Five (Short Cycles) are going to be your best bet at first.
• If you do have strong executive support, but you aren’t desperate to improve your organization, you might consider Option Three (Visible Negotiation).
• Of course, Option Six (Status Quo) is the easiest… I don’t really recommend it though!  Agility requires systematic change to encourage continuous improvement.  All the other options assist with this.

[This article was originally published on Agile Advice on 08-Jan-2012]

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