Time until delivery for good managers and customers is a range. Can you estimate getting 10kg of potatoes from grocery store that is 35m driving roundtrip away? Can you say it will be exactly 40mins because you can pick up and pay in 5 mins? I don't, I can say it will take between 40mins and 2h. There are always things like card terminal stops working or you get stuck in traffic because of an accident.
Complexity in that example is uncertainty like I do expect high traffic and there might be an accident happening but if there is less traffic and I hit all green lights 40mins going to be easy.
We all know bad managers and bad customers will expect me to get that bag of potatoes in 37 minutes and then ask 10x why did I not drove over that police officer that was stopping the traffic because of an accident to get their potatoes on time.
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"How much time will this take?"
"Not sure; approximately 30 minutes, but could also be 20 or 40 minutes. If we are very lucky then 10 minutes, but if we are very unlucky, maybe an hour or more."
"Spare me the details, I just need one number for the report."
"Uhm, 40 minutes?"
"You just said that it would be approximately 30 minutes, didn't you?"
"Yeah, but I wanted to add some safety margin..."
"If we keep adding large safety margins to everything, then the project will take forever. As you said, some tasks are completed faster, some tasks are completed slower, on average it will cancel out. I need your best estimate."
"Uh, okay, then 30 minutes. On average."
...the next week...
"So, you guys told me this would take 30 minutes, but it actually took 35. I think we need to have a serious talk about your performance."
Sometimes it's not. In the gaming industry Christmas is a hard deadline.
Instead, if you estimate complexity (e.g. I think this task is a 3, just as a starting point, then this task is roughly the same, so it's also a 3, then this one is similar but will take almost as much testing due to its difficulty, so we'll call it a 5, then this one is very simple, not even half as difficult as the first one, so it's a 1, etc), then try and keep that up for a few sprints, then figure out how many points fit into a sprint, you automatically factor in other factors (like "I have to log into Okta ten times a day", or "people keep getting pulled into meetings") through practical observation of what got done, and you get better at predicting what you'll be able to achieve in a sprint.
It's not perfect; it just removes the need for certain entire jobs devoted to accounting for time, which you can spend on another developer instead, while also being a reasonable measure of what you'll get done, and only takes about an hour every two weeks.
changing units and names of things really seems like a deliberate attempt to rob the discussion of any actual meaning. just a comfortable empty formalism that masks the fact that we aren't trying to come to grips with the most difficult parts of our job
If someone picks up task on Monday then has 20 other meetings - estimation is still the same, he just continues after those 20 meetings and you just don't care when estimating.
Only thing is if at the end of sprint dude is saying "I started X then I had 20 meetings so I did not make it" - well you just accept that or you don't put guy into 20 meetings.
You estimate tasks that way, but you estimate capacity to do tasks on your actual track record, which will include holidays and other things.
The confusion part is that by calling it "complexity" and saying it's not a time estimate you've muddied the waters on what it is, people will debate the definition and intentionally differentiate it from actual time. I've seen this before, the points-per-sprint never stabilizes because teams have cards where "that's a 1 point card because it's simple, but it will probably take a week". And then suddenly they're ignoring the points during planning to instead come up with an actual time estimates (which also don't work because they don't track those against multiple sprints).
But if a task is about 1 day, it may take 4 hours or 4 days, but it will almost certainly not be 1 month.
Points are always just a proxy for time, and work the same way. Not matter what anyone claims, as long as you use points to plan time-abound sprints, points are directly a measure of time.
At the same time, that's one of the reasons to prioritize removing as much uncertainty as possible.
- 3-4 weeks
- 3-9 weeks
Product managers can get their head around that.
Fundamentally, the problem is that project managers set deadlines based on statistical estimates from developers. Despite the fact that they set the deadline and do not understand the dispersion, they want developers to be responsible for misses. Sometimes, people mistankenly believe that there is some magical practice that can eliminate the uncertainty from estimation. You can make predictions with things like story points and achieve a certain amount of accuracy with a certain amount of dispersion. Statistically, it is the longitudinal behavior that can be predicted (sprint success rate at a specific velocity on a stable team), but we focus on cross sectional details (we missed this sprint).
Project management is generally not considered a field requiring statistical expertise but modeling reality of the work requires it.
Of course, there's actually no such thing as a "3 months give or take a week" estimate for a task. It's basically impossible in programming to have a task that takes that long with that low a level of uncertainty. So in reality, time estimates have the same properties as points: the higher a time estimate, the more uncertainty it represents.