If you have to estimate…

Single-point estimates are very often taken as promises, used as deadlines, create overhead, hides risk, becomes illusion of control.

Don’t use hours, f.ex do range-based estimates, think pair work, only focus on remaining work, adjust regularly.

F.ex when doing continuous forecasting, we need regularly updated capacity and remaining scope.

A few things to think about:

  • knowledge work, creative work, innovation is invisible, unpredictable to an extent, non-repetitive
    • we like to automate the repetitive, predictable…
  • the human brain have a lot of systematic biases
  • re uncertainty – average deviations from estimates accumulate upwards
  • pair (and mob) programming results in higher quality

Estimates, especially single-point estimates made when starting an effort and not adjusted continuously:

  • are very often taken as promises, used as deadlines
  • create overhead, waste
  • hides risk
  • becomes illusion of control

What we really need:

  • facilitate continuous discovery, planning, forecasting
  • understand work
    – common understanding of work, both within f.ex dev team and between business and software developers
  • early, real feedback
    – break down to minimum viable work items
  • mitigate risk, make decisions

So, when f.ex doing range-based estimation for continuous forecasting; for each broken down work item:

  • Don’t estimate hours – rather days
  • Think code review, pair programming, etc, working in pairs at least – not “single developer days”
  • Focus on remaining days continuously – don’t bother with “accounting” of spent time unless there’s a really good reason
  • Estimate (guess) a realistic amount of work, and call it “optimistic
  • Guess a pessimistic amount
    – and remember that uncertainty has a long tail upwards (there’s a limit for how much you can overestimate, but not for how much you can underestimate) and that our brains systematically work against us
  • Revisit estimates regularly, since you learn more about the work continuously – and only bother with remaining work


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