Earlier quoted context omitted.
>> Stop estimating. > How does this person think an organization schedule, budget and allocate resources? Collect data and use a trivial prediction model (i.e. median calendar time it took to complete the last 5 stories). Monitor and improve the prediction model over time if necessary. If you’re not collecting data reliably enough to generate a prediction automatically, you’re not taking any of these issues seriously…
That's just a way of estimating that is likely quite accurate in a completely steady state. But what if you know you're changing things significantly, and that's the whole point you need to think about resources and schedules? Like starting a new project?
Regardless, “collect and use data from the past,” does not require a “completely steady state,” and is pretty easy to modify. I’d feel a lot better having a conversation around, “this is totally new, do we think it will take about 2x or 5x longer than our normal projects?” Vs “this is totally new, so everyone guess how many months it will take without looking at any relevant data on either past project duration OR the accuracy of your past guesses.”
When people talk about “estimating task size” they almost invariably mean some planning-poker version of the second. Especially in TFA where they bring up forecasting as a better alternative.