Coaching practices for Bottom Up Estimation
Describe almost anything you are working through and IX Coach finds the practices whose real-world fit is closest. For Bottom Up Estimation, these are the strongest matches in the current practice library.
Does this sound like the set of challenges you might be facing?
- I glance at the whole thing and go "yeah, a weekend" without ever listing out the actual steps
- I build my estimate from my own optimistic story first and only glance at how long these things usually take at the very end as a sanity check
- The question is so big and tangled that I just go with my gut and blurt out a number, and it feels like a guess because it is one
- My guesses never seem to get any better because I make them, find out the real answer, and then just move on
- I land on a number and just go with it, never pausing to ask what’s the most it could possibly be or the least
Practices that may help
- Decompose tasks and sum the pieces
Estimate each sub-task independently, then add them up — the sum is closer to truth than a top-down estimate.
The Planning Fallacy — Why Your Estimates Are Always Wrong - Anchor on the base rate before adding inside-view details
Start your forecast from the class median, then adjust — do not start from your narrative and adjust to the base rate.
Reference Class Forecasting - Decompose complex questions into sub-questions
Break a hard forecasting question into smaller, estimable pieces and aggregate them.
Superforecasting - Track your estimates and calibrate
Compare your Fermi estimates to actual figures when you can, and use the gap to improve future estimates.
Fermi Estimation - Sanity-check against known extremes
Test your estimate against the clearly too-high and too-low bounds to calibrate your range.
Fermi Estimation - Fermi Estimation
Fermi estimation is the practice of making rough but principled quantitative estimates by decomposing an unknown into knowable sub-problems, estimating each, and combining them. Named for physicist Enrico Fermi, who was renowned for accurate estimates from minimal data, it is used in science, engineering, and everyday decisions to calibrate intuitions and check whether a number is in the right ballpark — not to achieve false precision. - Watch for anchoring
Recognize when an arbitrary first number is silently dragging your estimate.
Thinking, Fast and Slow, Made Usable - Use reference class forecasting for project estimates
Estimate how long similar projects have taken historically before estimating your specific project.
Base-Rate Neglect: Why We Ignore the Odds - Check units and scales for consistency
Catch order-of-magnitude errors by ensuring your units are consistent across the estimate.
Fermi Estimation - Log actual vs. estimated time for every task
Build a personal database of your own estimation errors so you can calibrate future predictions.
The Planning Fallacy — Why Your Estimates Are Always Wrong
Related concerns
- How To Estimate Anything
Test your estimate against the clearly too-high and too-low bounds to calibrate your range.
Sanity-check against known extremes
- Independent Estimates Aggregation
Combine independent estimates from multiple people before the group talks — aggregation beats any single expert.
Use structured team forecasting to aggregate diverse views
- Time Estimation Accuracy
Build a personal database of your own estimation errors so you can calibrate future predictions.
Log actual vs. estimated time for every task
- Units In Estimation
Catch order-of-magnitude errors by ensuring your units are consistent across the estimate.
Check units and scales for consistency
- Decomposition Estimation
Fermi estimation is the practice of making rough but principled quantitative estimates by decomposing an unknown into knowable sub-problems, estimating each, and combining them. Named for physicist Enrico Fermi, who was renowned for accurate estimates from minimal data, it is used in science, engineering, and everyday decisions to calibrate intuitions and check whether a number is in the right ballpark — not to achieve false precision.
- Fermi Estimation When Starting Out
Compare your Fermi estimates to actual figures when you can, and use the gap to improve future estimates.
Track your estimates and calibrate
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