Home › Methodology
Methodology
How we collect, calculate and present every piece of information on this site. We aim for total transparency: every metric below has a source, a refresh cadence, and a declared limitation.
One sentence summary: we ingest open government data each month, link records by their official identifiers (URN for schools, LSOA for deprivation), recompute every metric from raw figures, and rebuild the static site from the result. Nothing on this site is hand-entered. Every page tells you when the data was last refreshed.
Refresh cadence
The full data pipeline runs automatically on the 15th of every month at 08:00 UTC via GitHub Actions. The pipeline:
- Fetches fresh data from each source listed below.
- Joins records by their official identifiers (DfE URN, LSOA code, postcode).
- Recomputes every derived metric (ratios, averages, distances).
- Rebuilds all 3,196 school pages, 33 borough hubs, and the homepage.
- Updates the XML sitemap with the new
lastmodtimestamp. - Commits the rebuilt site to GitHub and triggers a Vercel deploy.
The full run log for every refresh is public on our GitHub Actions history. If a source is temporarily unavailable on refresh day, the previous month's figures are retained with a clear "data last verified" stamp.
School identifiers
Every school is identified by its DfE Unique Reference Number (URN), which is the canonical identifier used across all UK education datasets. We never deduplicate or merge URNs. If a school changes name, type, or trust, its URN persists, so we preserve the historical record.
Per-metric methodology
Ofsted rating
| Source | Ofsted Management Information |
|---|---|
| What we publish | The most recent overall effectiveness rating: Outstanding, Good, Requires Improvement, or Inadequate. The date of the inspection that produced it. |
| Refresh | Monthly, on the 15th, from the Ofsted MI dataset. |
| Limitations | Ratings are inspection-based and reflect a moment in time. Since September 2024, Ofsted has paused single-word overall judgements for state schools and is moving towards subject-level reporting. We display the most recent overall judgement available for each school; where Ofsted has not yet inspected a school since the change in framework, we display the last published rating and the inspection date. Independent schools are inspected by ISI, not Ofsted; their ratings use a different scale. |
Key Stage 2 attainment and progress
| Source | DfE Explore Education Statistics — KS2 attainment |
|---|---|
| What we publish | The latest published progress and attainment measures for reading, writing and maths. Where a school has a value, we show it; where the school is too small for a value to be published (suppressed for statistical reliability), we show "—". |
| Refresh | Annually, when the DfE publishes the revised KS2 release (typically December). |
| Limitations | Tests were cancelled in 2020 and 2021 due to the pandemic. For those years, no data is published. We do not impute or backfill. |
Key Stage 4 (Attainment 8 and Progress 8)
| Source | DfE EES — KS4 performance (revised) |
|---|---|
| What we publish | Latest published Attainment 8 score and Progress 8 score where available. |
| Refresh | Annually on the DfE revised release (typically January–February). |
| Limitations | The pandemic disrupted GCSE assessment in 2020 and 2021. The DfE has indicated that Progress 8 should be compared between schools with caution for those years. Small schools may have figures suppressed. |
Applications per place
| Source | DfE EES — School applications and offers |
|---|---|
| What we publish | Number of first-preference applications per available place for the most recent admissions cycle. |
| Refresh | Annually, typically June. |
| Limitations | This is a useful indicator of demand but not a predictor of any individual family's chance of admission, because each school applies its own oversubscription criteria (catchment distance, sibling priority, faith, banding). For grammar schools, an application is only meaningful if the child has met the test threshold. |
Crime within 500 metres
| Source | Metropolitan Police open data API (data.police.uk) |
|---|---|
| What we publish | Number of recorded crime incidents within a 500-metre radius of the school's location, in the most recent reporting month, by broad crime category. |
| Refresh | Monthly, on the 15th, using the most recent month for which data is published (usually with a 1–2 month lag). |
| Limitations | This is reported crime in the surrounding area, not crime in the school itself. It reflects population density and footfall as much as community safety. We strongly encourage families to interpret this figure as one data point among many. The Met publishes incidents to the centre of the nearest street to protect victim privacy, so figures are approximate. |
Index of Multiple Deprivation (IMD) decile
| Source | MHCLG English Indices of Deprivation 2019 |
|---|---|
| What we publish | The IMD decile of the Lower Super Output Area (LSOA) in which the school is located. 1 = most deprived 10% of LSOAs in England; 10 = least deprived. |
| Refresh | The IMD is updated every four to five years by central government. The current dataset is IMD 2019; a new edition is expected. |
| Limitations | The IMD describes the small area around the school, not the catchment population of the school itself. Many schools draw pupils from areas with different IMD scores. |
Admissions appeals (success rates)
| Source | DfE EES — Admission appeals |
|---|---|
| What we publish | Borough-level success rates for Reception and secondary-transfer appeals heard, by academic year, 2016 to the latest published year. |
| Refresh | Annually, typically the autumn following the academic year. |
| Limitations | Published at local authority level only — the DfE does not release school-level appeal outcomes. Numbers can be small for some boroughs in some years. |
Ranking — how we order schools
Where we present a top-N list on a borough hub page, we order schools by:
- Ofsted rating (Outstanding > Good > Requires Improvement > Inadequate).
- Within the same rating, by latest KS2 progress (for primary schools) or KS4 Attainment 8 (for secondary schools).
- Tie-broken by applications per place.
This is a deliberately simple, transparent rule. We do not weight, smooth, or apply any proprietary score. The full ordering logic is visible in the open-source build script.
Known limitations
- This site lists state-funded schools and a small number of public-record independent schools. We do not yet exhaustively cover independent schools, sixth-form colleges, or further education colleges.
- Performance data is necessarily backward-looking. A school that was rated Outstanding three years ago may be a different school today.
- Crime, IMD, and applications-per-place figures are area-level signals. They are useful as context, not as predictors of individual outcomes.
Corrections
If anything on the site is inaccurate, please tell us. Email thierrysw11@gmail.com with the URL of the page and the issue. We aim to verify and respond within 5 working days. Every correction we make is logged in our public corrections log.
Version history
This methodology is versioned. Significant changes are recorded with date and rationale in our GitHub history.