Posted: October 5, 2017 Filed under: flow | Tags: cost of delay, kanban
- The “Big Four” cost of delay profiles (a.k.a. archetypes) — Expedite, Fixed-Date, Standard Urgency, Intangible — are usually sufficient.
- In my personal kanban, I have seen a new archetype emerge, one that has aspects of both Intangible and Fixed-Date, which I’m calling “Intangible-Fixed-Date.”
- This profile is less for the purpose of selection and more for scheduling.
- So far, the main application of “Intangible-Fixed-Date” for me is for buying airfare, whose cost-of-delay curve fits none of the “Big Four” curves.
- I use a couple of features in Kanbanize to deal with this new profile slightly differently from the other profiles, namely by creating a separate swim lane and using two dates (rather than one).
- Takeaway: “Listen” to your data, patterns and behavior of work items and be flexible enough to adapt and create new profiles when they emerge.
I routinely use cost-of-delay to assist in scheduling, selecting and sequencing work, both in professional settings and in my own personal life. The “Big Four” cost-of-delay profiles (aka archetypes) promoted in the Kanban community — Expedite, Fixed-Date, Standard Urgency, Intangible — are usually sufficient for the work that organizations, teams and I personally need to handle. However, lately in my personal kanban, I have seen a new archetype emerge, one that has aspects of both Intangible and Fixed-Date, which I’m calling “Intangible Fixed-Date.”
Basically, the new profile has arisen from the need to handle airfare purchasing, something that I do somewhat often. Since I’m not independently wealthy and I like to do right by my employer when I’m traveling on business, I care about the cost of airfare. Anyone who travels knows that there is some optimal time to buy airfare (even if he or she doesn’t know exactly when that is). I want to be able to research fares just-in-time to get the best deal. However, if I model the task as a simple fixed-date item, I either have to use the true date by which the cost-of-delay is unacceptable (that is, the day I need to be somewhere) or use a fake deadline. I typically added the task to my Fixed-Date lane with its true deadline, then would occasionally check it to see if it “felt” like I should act, but it was too easy to forget about it until past a responsible moment, even if it wasn’t the last responsible moment. Which brings us to the crux of the problem: This type of item has two last responsible moments, the financially last responsible and absolute last.
Let’s review the cost-of-delay curves of the existing profiles:
According to the reliable Andy Carmichael
and David Anderson in their Essential Kanban Condensed
, Fixed-Date items “have high impact but only if you miss the deadline. The scheduling imperative here is to make sure you start before the last responsible moment and deliver before the deadline.” Also, you don’t get any economic benefit from completing the work before the deadline. In software delivery, this usually means understanding how long it can take you to complete the work (see your handy delivery-time histogram), then backing up from the deadline from there based on risk tolerance. However, booking airfare doesn’t take much time (I can do it in a few minutes) — so that’s not a concern. But the deadline only represents the absolute last responsible moment, so this curve is insufficient.
If airfare price increases were linear, I could use a standard urgency profile blended with the fixed-date. But some basic research shows that price increases have an inflection point somewhere around the 30-day mark, although the lowest prices may occur earlier:
Other factors matter, too, of course (seasonality, specific locations). But I don’t need to get too deep into modeling that yet — I just need a better solution. That means incorporating the Intangible curve, whose items “have an apparently low urgency,” but that indicates “a rise in urgency – possibly a steep rise – will happen in the future.”
My airfare purchases exhibit aspects of both curves, though neither is sufficient. Unlike a typical intangible item, I actually do know when that future date will be, along with a rough idea of when the “rise in urgency” will happen. And unlike a typical fixed-date item, there is some economic benefit from doing it sooner than the deadline.
Intangible Fixed Date
Now that I understand the cost-of-delay curve, I need to be able to handle it in my kanban system. One approach that I’m trialling is to create a separate swim lane — “Intangible Fixed-Date” — and use a second date to signal readiness (the second date being my optimal time to commit).
Here’s how it works: Say I find out on Sep. 6 that have to be in Chicago on Nov. 6. That’s two months away. Given that airfare cost won’t typically rise until about 30 days out, I don’t want to worry about this yet, which is to say, I don’t want this card on my Requested column yet. So I set up a rule in Kanbanize
(my work-visualization tool of choice) to keep it in the backlog until 35 days out (the five-day buffer allows me some flexibility), at which time it moves the card from the backlog to Requested.
It has the ultimate deadline — Nov. 6 — displayed on the card. But since it’s in its own swim lane, I have an explicit policy that I begin work on these items as soon as they appear in Requested.
If I want to really be disciplined, I can then set a service-delivery expectation that sets the bar for how well I handle these (e.g., 90% of Intangible Fixed-Date items will be completed within five days), and analyze my performance at my personal service-delivery review. But now I fear I’m exposing just how geeky I am (if that wasn’t clear already)!
So what’s the takeaway? Well, you might find value in this “new” cost-of-delay profile (if you need to book airfare, or to plan birthdays or anniversaries, which follow a similar curve). But abstracting out a bit, the idea is that it’s helpful to pay attention to — “listen” to — your data, patterns and behavior of work items and be flexible enough to adapt and create new profiles when they emerge. Pursuing incremental, evolutionary change is one of the underlying principles of kanban method; improve using models and experiments is one of its core practices.
Special thanks to Prateek Singh, Josh Arnold and Mike Burrows for their early feedback in the Lean Agile and Beyond Slack community.