THE INDEX · DO SYNTHETIC PEOPLE BEHAVE LIKE REAL ONES?
Kendall Square world
- IN PROGRESS
- HELD-OUT BENCHMARK
QUESTION
Without tuning any constant to the outcome it is scored against, how close does the same pipeline get in another city?
SYSTEM
The pipeline that built Andorra’s population, pointed at the City of Cambridge, Massachusetts, around Kendall Square: 118,403 residents in 67,034 households across 564 populated cells, and 141,368 inbound commuters. It follows three rules: the machinery stays country-agnostic, nothing is calibrated on the held-out outcome, and it has to work where data are thin.
Adding another place requires a new pack and compatible assets, not an engine fork.
EVIDENCE
On the held-out benchmark, the reference run misses the census work-leg mode split by 29.4 points, and walks 9.6% of work legs against 28.2% in the census. It matches the mean travel time to work: 25.9 against 25.8 minutes.
- WALKED WORK LEGS · 9.6% VS 28.2% (CENSUS)
- TIER 3.1 · NOT ADOPTED (ONE METRIC WORSENED)
Fitting intercepts moves the miss, it does not remove it.
STATUS AND LIMITS
A variant with timetabled transit (tier 3.1) made the mode-split miss worse, 29.41 to 30.11 points, so it was not adopted. Any trips drawn on the map come from its demo export: experimental, not adopted. Non-work trips have no held-out test yet. Every person in this world is fictional; of the population, only counts per cell and a sample of trip legs leave the private repository.
CREDITS
Census geography: U.S. Census Bureau. Street and path geometry © OpenStreetMap contributors (ODbL). Transit timetables and shapes: MBTA GTFS.
SOURCES AND STATUS FOR THIS PAGE · 11 CLAIMS
| Claim | Status | Source | Checked |
|---|---|---|---|
| Without tuning any constant to the outcome it is scored against, how close does the same pipeline get in another city? | OWN WORDING | Kendall Square world README, frozen commit (private repository) | 2026-10-10 |
| The pipeline that built Andorra's population, pointed at the City of Cambridge, Massachusetts, around Kendall Square: 118,403 residents in 67,034 h… | OWN WORDING | Kendall Square world README and tier2 run_meta, frozen commit e94f175 (private repository); public/data/kendall-cells.json totals | 2026-10-13 |
| Adding another place requires a new pack and compatible assets, not an engine fork. | OWN RECORD | README of my coupling repository (private) | 2026-10-10 |
| On the held-out benchmark, the reference run misses the census work-leg mode split by 29.4 points, and walks 9.6% of work legs against 28.2% in the… | OWN WORDING | Kendall Square world README and held-out benchmark v2 (tier2, the reference arm), frozen commit e94f175 (private repository); public/data/kendall-cells.json facts | 2026-10-13 |
| WALKED WORK LEGS · 9.6% VS 28.2% (CENSUS) | DERIVED FROM DATA | Kendall Square world README (private repository) | 2026-10-13 |
| TIER 3.1 · NOT ADOPTED (ONE METRIC WORSENED) | DERIVED FROM DATA | Kendall Square world README (private repository) | 2026-10-13 |
| Fitting intercepts moves the miss, it does not remove it. | OWN RECORD | HOW_WE_BUILT_IT, section 8 (own repository) | 2026-10-10 |
| A variant with timetabled transit (tier 3.1) made the mode-split miss worse, 29.41 to 30.11 points, so it was not adopted. Any trips drawn on the m… | OWN WORDING | Kendall Square world README, docs/TIER3.1_DEMO.md and tier2 run_meta limitations, frozen commit e94f175 (private repository); public/data/kendall-*.json | 2026-10-13 |
| Census geography: U.S. Census Bureau. Street and path geometry © OpenStreetMap contributors (ODbL). Transit timetables and shapes: MBTA GTFS. | DERIVED FROM DATA | Attribution strings of public/data/kendall-cells.json, kendall-trips.json and kendall-transit.json | 2026-10-13 |
| IN PROGRESS | OWN RECORD | Kendall Square world repository (private) | 2026-10-10 |
| HELD-OUT BENCHMARK | OWN RECORD | Kendall Square world README (private repository) | 2026-10-10 |