The Product Backlog: A Journey In The Mist

Man walking in the mistI’ve been working on reviewing an upcoming agile book and there’s a nice discussion in it about the various metaphors that people use to describe product backlogs in Scrum.  They all get the point across, but I thought I’d try to come up with an alternate visualization.  And then I had a dream about it (really)!

Something’s Bugging Me About Icebergs

One of the most common backlog metaphors is the iceberg , where a small percentage of the backlog is very well defined and visible at the top (this math says it’s about 13% for actual icebergs) and the rest is progressively more coarse-grained and murky as you go down, until at the bottom you’ve got Big Ideas For The Future that aren’t clear at all.  The idea is that this is a good thing, because Lean principles tell us not to spend too much time worrying about low priority features we may never build.  However …

Let’s play a quick word association game.  ICEBERG!!

icebergI bet you thought “Titanic”.  So did I.  It turns out that the 87% of the iceberg that’s below the water is a big problem if you’re trying to navigate.  In the case of an iceberg, it’s actually *not* ok that we don’t know much about what’s down there, whereas with software development we’ve got to accept that and deal with it.  Also we can’t see the underwater part at all without special sensing equipment – versus the sprint/current release/future release gradation of a backlog – so the analogy kind of breaks down.

Stories In The Mist

So, here’s my metaphor for the backlog:  You’re walking through a misty landscape where the fog obscures your view beyond a few dozen yards.  You need to get to your destination – a small rural town which you know lies to the north – but you can’t see it.  You do have a compass to point the way, though.  You know you’ll have to cross rivers, rocky areas, and other obstacles but again, most of them are hidden from view.  Luckily, the colors and details of closer features stand out crisply against the white background.  You see some rocks and roots in the path and an incline to climb, so you note them as the most important and move forward.

As you reach the top of the small slope, more features emerge from the mist, and now you can see some vague larger shapes in the distance, including what looks like a foot bridge over a river.  You pick that as your goal and as you keep going, more trees and rocks reveal themselves with enough fidelity that you can navigate past them.

You doggedly hike on in the right general direction, picking short and medium distance goals and stopping every now and then to rest and check your compass.  Eventually you begin to see lights piercing through the mist in the distance and this gives you energy to quicken your pace, knowing that you’re almost there.  You hear the sounds of the town emerge: car tires on pavement, a dog barking, and you step out of the fog and the woods onto the main road leading into the town proper.  You’re just a mile away from a comfortable bed and a satisfying meal.  You did it!

What I Like About This

I like this metaphor because it emphasizes that while it’s important to have long-term goals (heading north to the town), most of the effort is in assessing the immediate and imminent surroundings to make good tactical decisions:  step over these roots, head for that bridge, etc.  It also adds a sense of movement.  You’re constantly traveling forward as you achieve small milestones, and that movement itself is what reveals and clarifies the next steps.  Even if you have some prior knowledge of the landscape, there are going to be surprises and that’s ok.  A bridge is out; a path is washed out by a storm or blocked by a tree.  There are no guarantees that the set of actions you end up taking to meet the goal are the same ones you expected to take.

What do you think?  Is this a useful way to think about the backlog?  Leave me a comment and let me know!

stones on foggy river


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