diff --git a/.claude/JOURNAL.md b/.claude/JOURNAL.md index c64a9c6..1a34c75 100644 --- a/.claude/JOURNAL.md +++ b/.claude/JOURNAL.md @@ -252,3 +252,6 @@ This journal tracks substantive work on documents, diagrams, and documentation c 83. **Task - Activity monitor half-life to 72h (3 days)**: Extended decay half-life for smoother scoring
**Result**: Updated JUPYTERHUB_ACTIVITYMON_HALF_LIFE default from 48h to 72h across Dockerfile, custom_handlers.py, activity_sampler.py, settings_dictionary.yml, README.md, and docs/activity-tracking-methodology.md. Added rationale section explaining why 72h: decay applies to wall-clock time, not working time. A user working 8h/day is active only 1/3 of each 24h period - with 72h calendar half-life, ~24 working hours (3 days × 8h) have 50% weight, effectively calibrating decay to one full workday of engagement. This prevents overnight breaks from aggressively penalizing scores + +84. **Task - Half-life simulation tables**: Added detailed simulation results to documentation
+ **Result**: Ran Python simulation for different work patterns (10h, 8h, 4h per day) across calendar half-lives (24h-168h). Added three tables to docs/activity-tracking-methodology.md showing "Work Hours at 50%" and "Work Days at 50%" for each combination. Key finding: 72h calendar half-life consistently yields ~2.9 work days at 50% point regardless of daily work hours. Activity scores correctly reflect work fraction (10h=41.6%, 8h=33.3%, 4h=16.6%) diff --git a/docs/activity-tracking-methodology.md b/docs/activity-tracking-methodology.md index c7ee1bc..071efb6 100644 --- a/docs/activity-tracking-methodology.md +++ b/docs/activity-tracking-methodology.md @@ -11,19 +11,57 @@ Our current approach uses **exponential decay scoring**: ### Why 72-hour Half-life? -The decay applies to **wall-clock time**, not working time. A typical user works 8-9 hours per day - roughly 1/3 of a 24-hour period. This creates a mismatch between calendar decay and effective working activity decay: +The decay applies to **wall-clock time**, not working time. Users work only a fraction of each 24-hour period, creating a mismatch between calendar decay and effective working activity decay. -| Calendar Half-life | Working Hours in Period | Effective Work Half-life | -|--------------------|-------------------------|--------------------------| -| 24 hours | ~8 hours | ~8 hours of work | -| 72 hours (3 days) | ~24 hours | ~24 hours of work | +#### Simulation Results + +The following tables show how different calendar half-lives translate to effective working-time decay for various work patterns. "Work Hours at 50%" indicates how many actual working hours contribute 50% of the weighted activity score. + +**10h/day work pattern** (intensive) + +| Calendar Half-life | Work Hours at 50% | Work Days at 50% | Activity Score | +|:------------------:|:-----------------:|:----------------:|:--------------:| +| 24h (1d) | 10.0h | 1.0 days | 41.0% | +| 48h (2d) | 19.8h | 2.0 days | 41.5% | +| 72h (3d) | 28.5h | 2.9 days | 41.6% | +| 96h (4d) | 35.3h | 3.5 days | 41.6% | +| 168h (7d) | 47.7h | 4.8 days | 41.7% | + +**8h/day work pattern** (typical) + +| Calendar Half-life | Work Hours at 50% | Work Days at 50% | Activity Score | +|:------------------:|:-----------------:|:----------------:|:--------------:| +| 24h (1d) | 8.0h | 1.0 days | 32.7% | +| 48h (2d) | 16.0h | 2.0 days | 33.2% | +| 72h (3d) | 22.8h | 2.9 days | 33.3% | +| 96h (4d) | 28.3h | 3.5 days | 33.3% | +| 168h (7d) | 38.2h | 4.8 days | 33.3% | + +**4h/day work pattern** (part-time) + +| Calendar Half-life | Work Hours at 50% | Work Days at 50% | Activity Score | +|:------------------:|:-----------------:|:----------------:|:--------------:| +| 24h (1d) | 4.0h | 1.0 days | 16.3% | +| 48h (2d) | 8.0h | 2.0 days | 16.6% | +| 72h (3d) | 11.5h | 2.9 days | 16.6% | +| 96h (4d) | 14.2h | 3.5 days | 16.6% | +| 168h (7d) | 19.2h | 4.8 days | 16.7% | + +#### Summary: 72-hour Half-life Across Work Patterns + +| Work Pattern | Work Hours at 50% | Effective Work Days | Activity Score | +|:------------:|:-----------------:|:-------------------:|:--------------:| +| 10h/day | 28.5h | 2.9 days | 41.6% | +| 8h/day | 22.8h | 2.9 days | 33.3% | +| 4h/day | 11.5h | 2.9 days | 16.6% | + +#### Key Insights With a 72-hour calendar half-life: -- A user working 8h/day accumulates ~24 hours of working time over 3 calendar days -- Activity from those 24 working hours has 50% weight -- The decay is effectively calibrated to **one full workday** of actual engagement - -This makes scores more stable for users with typical work patterns. A 24-hour half-life would be too aggressive - yesterday's full workday would already be at 50% weight before today even starts, penalizing normal overnight breaks +- **Consistent ~3 work days** at the 50% point regardless of daily work hours +- Activity score reflects actual work fraction (8h/24h ≈ 33%, 4h/24h ≈ 17%) +- Overnight breaks don't aggressively penalize scores +- A 24-hour half-life would be too aggressive - yesterday's work already at 50% weight before today starts ## Industry Approaches