EP-04
Story Points vs Time Spent — Non-Linear Scaling
Estimation Precision
Default severity: medium
EstimationQualityBusiness ValueEffort
What it detects
The relationship between story points and actual time is not linear — larger SP issues take disproportionately longer than smaller ones (or the reverse). A 13-point story should take roughly 2.6x a 5-point story; if the ratio is 5x or 1.5x, the SP scale is not calibrated correctly.
Detection formula
FOR each_sp_pair (C_small, C_large) WHERE C_large > C_small: expected_ratio = C_large / C_small actual_ratio = MEDIAN(time_spent, sp=C_large) / MEDIAN(time_spent, sp=C_small) IF actual_ratio / expected_ratio > config.ep.scaling_nonlinearity_threshold // default: 2.0 OR actual_ratio / expected_ratio \< 1/config.ep.scaling_nonlinearity_threshold THEN FLAG non_linear_scaling for pair (C_small, C_large) Report: complexity chart matrix of actual ratios vs expectedExamples in practice
- A team shows the relationship between story points and actual time is not linear while scaling nonlinearity threshold is set to 2.0.
- Example signal: The relationship between story points and actual time is not linear — larger SP issues take disproportionately longer than smaller ones (or the reverse).
Suggested response
Recalibrate estimation precision—check size classes, drift, and BV vs effort trade-offs.
Coaching playbook
Symptom
The relationship between story points and actual time is not linear — larger SP issues take disproportionately longer than smaller ones (or the reverse). A 13-point story should take roughly 2.6x a 5-point story; if the ratio is 5x or 1.5x, the SP scale is not calibrated correctly.
Why it matters
When "Story Points vs Time Spent — Non-Linear Scaling" keeps appearing, the team is signalling a repeatable process gap. Left unexamined, the pattern hides where work really stalls and makes improvement metrics harder to trust.
What you can achieve
Recalibrate estimation precision—check size classes, drift, and BV vs effort trade-offs.
Facilitation questions
- What system change would stop "Story Points vs Time Spent — Non-Linear Scaling" from firing again?
- What do the cited issues have in common — same root cause or same workaround?
- Who owns the two-week experiment and how will we verify on the next import?
Run this rule against your own tracker data with Flow Analyzer.