The PTAL Contradiction

London’s official transport score says how well-connected you are. It does not say whether you are the one who always travels further to see your friends.

Awaiting a production run. Pre-registration is locked in docs/experiments/ptal-contradiction-preregistration.md. Numbers, map, and CSV appear here only after robustness checks pass. Dry-run geometry proxies are never published.

Headline number

R² between PTAL and origin disadvantage (MFS-O) — placeholder until the full run.

Metric	Value
R² (PTAL vs MFS-O)	—
Panel	1,000 groups × 3–5 people (pre-registered)
Publish geography	Ward (analysis at LSOA)

Quadrant tables

Top 10 wards in each off-diagonal quadrant — filled after publish decision.

Quadrant	Meaning	Top wards
High PTAL · High MFS-O	Well-connected, still always travels further	—
Low PTAL · Low MFS-O	Badly connected on paper, conveniently placed for friends	—

Map

Side-by-side PTAL vs disadvantage map ships with the published CSV. Not shown until results exist.

Method

Pre-registration committed before analysis.
Scoring: production FairWhere / FairPath (estimate_only + FairWhere Score fair weights).
Origins: population-weighted LSOA sample; no user data.
Destinations: published Placelists + meeting-point landmarks.
Four robustness checks required (second seed, second departure, exclude >90 min, drop PTAL 0/1a).

FairPath public organic MAPE is not yet published; times are planning estimates. Confirm journeys with live TfL before travelling.

Limitations

Simulated friendship groups, not observed ones.
Venue set limited to published Placelists / landmarks.
Single network snapshot; PTAL vintage 2023.
Does not claim PTAL is wrong — only that connectivity ≠ social-journey disadvantage.

Downloads

CSV will match the HTML table exactly when published. Placeholder file:

results.placeholder.csv

Powered by TfL Open Data
Using TfL open data. Not affiliated with, endorsed by, or an official project of Transport for London.
Contains public sector information. Where Ordnance Survey–derived content appears in republished artefacts: Contains OS data © Crown copyright and database rights 2026.