# Compare Screen Redesign — Audit & Design

**Date:** 2026-07-11
**Status:** Draft — awaiting review
**Scope:** `/compare` page (nextjs-app), `/api/compare` endpoint (backend)

## 1. Audit of the current screen

The current compare page (`nextjs-app/components/ComparisonView.tsx`) is a
single-metric analyst tool: a `<select>` with ~40 KS2/GCSE metrics, one
line chart over time, and a year-by-year table — all for the one selected
metric. Observed on production with 3 primary schools:

**What works**

- URL-shareable state (`?urns=…&metric=…`), native share sheet.
- Phase tabs (primary/secondary) with sensible auto-detection.
- Colour-coded school cards tied to chart series.
- Metric descriptions from `/api/metrics` (single source of truth).

**What doesn't**

1. **Performance-only.** The database already holds Ofsted inspections,
   admissions/oversubscription history, pupil characteristics (FSM/EAL),
   SEN, deprivation (IDACI), finance, capacity, faith, gender, trust —
   none of it reaches the compare screen. `/api/compare` returns only
   `yearly_data` + minimal `school_info`, while `/api/schools/{urn}`
   already returns all supplementary blocks.
2. **One metric at a time.** A parent must know which of ~40 metrics
   matters, select each in turn, and hold results in their head. There is
   no side-by-side overview and no way to see two dimensions at once.
3. **No benchmarks.** Numbers float without anchors: is 79% RWM good?
   The DB has official national averages (`fact_ks2_national_averages`)
   but the page never shows them.
4. **Domain jargon untranslated.** "GPS Expected %", "Progress scores",
   "RWM Combined" assume DfE literacy. The only plain-English help is one
   note for progress scores.
5. **Raw numbers, no judgement support.** 87.0% vs 92.0% vs 79.0% — the
   page never says "all three are well above the England average of 62%",
   which is the fact a parent actually needs.
6. **Bugs/paper cuts observed:** the third school's series did not render
   on the production chart despite table data (worth a separate fix);
   the COVID gap (2018/19 → 2022/23) renders as equal spacing with no
   annotation; table shows "87.0%" precision that implies false accuracy.

## 2. Data inventory (available vs shown)

| Domain | Source table | On detail page | On compare |
|---|---|---|---|
| KS2 attainment/progress | fact_ks2_performance | yes | **yes** (only thing shown) |
| National averages | fact_ks2_national_averages | partial | no |
| Ofsted (latest + subgrades + report-card fields) | fact_ofsted_inspection, dim_school | yes | no |
| Admissions & oversubscription (multi-year) | fact_admissions | yes | no |
| Pupil characteristics (FSM, EAL, gender split) | fact_pupil_characteristics | yes | no |
| Context (SEN, disadvantaged, stability, absence) | fact_ks2_performance | via metric picker | buried in picker |
| Deprivation (IDACI) | fact_deprivation | yes | no |
| Finance (per-pupil spend) | fact_finance | yes | no |
| School facts (capacity, faith, ages, trust, nursery, gender) | dim_school | yes | no |
| Location/distance | dim_location | map | no |

## 3. Design goals

1. **Answer parent questions, in order:** Is it a good school (Ofsted)?
   Do children do well there (academics vs England)? Will my child get a
   place (admissions)? What is the school like (size, community, faith)?
2. **Every number gets an anchor** — the England average, rendered as a
   consistent visual tick, plus a plain-English chip
   (Above / Close to / Below England average).
3. **Plain English first, jargon on demand.** Labels are questions or
   sentences ("Children reaching the expected standard in reading,
   writing and maths"), codes/acronyms live in tooltips.
4. **Scan whole-picture first, drill down second.** The single-metric
   trend explorer survives, demoted to an "Explore trends" section at the
   bottom rather than being the entire page.

## 4. Proposed structure

Columns = schools (max 4 visible on desktop, horizontal scroll beyond),
rows = dimensions. Sticky compact school header keeps column identity
while scrolling. Sections, in order:

1. **At a glance** — verdict row per school: Ofsted badge, headline
   attainment vs England (dot strip + chip), oversubscription chip,
   size, distance (when a location is set).
2. **Ofsted inspection** — must handle all three inspection regimes,
   which will coexist in comparisons for years:
   - **Legacy graded (pre-Sept 2024):** overall grade badge
     (Outstanding/Good/Requires improvement/Inadequate). Subgrades,
     where published, are rendered in the **same area-by-rating chip
     list UX as report cards** (one row per judgement area, rating as
     a chip) — one visual grammar for inspection detail across both
     regimes. Where our dataset has no subgrades for an inspection,
     say so honestly ("We don't hold area-by-area detail for this
     inspection") and point to the school's Ofsted page — never claim
     the inspection itself published no detail (graded inspections
     always have subgrades; if it was ungraded, the grade is
     carried forward and must be labelled as such).
   - **Interim ungraded (Sept 2024 – Nov 2025):** parsed outcome
     ("remains Good") shown as the effective grade, marked as such.
   - **Renewed framework report card (from Nov 2025):** no overall
     grade exists. Render the report card as an area-by-rating list
     using Ofsted's 5-point scale (Exceptional / Strong standard /
     Expected standard / Attention needed / Urgent improvement) across
     the evaluation areas we model (`rc_inclusion`,
     `rc_curriculum_teaching`, `rc_achievement`,
     `rc_attendance_behaviour`, `rc_personal_development`,
     `rc_leadership_governance`, `rc_early_years`, `rc_sixth_form`)
     plus the separate safeguarding met/not-met flag. **At-a-glance
     summary rule:** never an unlabelled colour strip — summarise by
     counting areas per rating, best first ("5 areas Strong standard ·
     3 areas Expected standard"), and always name any area rated
     Attention needed or Urgent improvement explicitly (never fold
     problems into a count), plus "Safeguarding not met" whenever that
     flag is false. When everything is Expected standard or better,
     add the reassurance line "No areas need attention".
   When a comparison mixes regimes, show a one-line comparability note
   ("Ofsted changed how it reports in Nov 2025 — a report card and an
   older overall grade aren't directly comparable"). Never derive a
   fake overall grade from report-card areas.
3. **Academics (KS2)** — one dot-strip row per headline measure (RWM
   expected, RWM higher, reading/writing/maths expected), each with the
   England-average tick and per-school dots; copy must say "tests and
   teacher assessments" (writing is TA, not a test). Progress scores
   translated to Above/Average/Below chips (CI-based) — **but note KS2
   progress measures ended with 2022/23** (no KS1 baseline afterwards)
   and return only when the reception-baseline cohort reaches Y6
   (~2027/28), so progress chips apply to historical years in the
   trends explorer, not the headline view. Sparkline per school over
   the full published period, with an honest gap for the cancelled
   test years (2019/20–2020/21). Disadvantaged-pupils row under an
   "Equity" subheading, always with cohort size shown and DfE's full
   definition (FSM6 **or** looked-after/previously looked-after).
4. **Getting a place** — oversubscription ratio as plain sentence
   ("184 applications for 80 places"), first-preference success %, trend
   vs last year, admissions policy.
5. **Who goes there** — pupils on roll (vs capacity), boys/girls, FSM %,
   EAL %, SEN support %, faith, ages, nursery, trust. *Post-v1:* IDACI
   decile in words (needs a coverage check of `fact_deprivation` and
   the neighbourhood-not-school caveat, §8.7).
6. **Attendance** — *post-v1.* The KS2 test-day absence fields are the
   only per-school absence data we hold; they're near-zero for most
   schools and easy to misread as general attendance. Ship only if a
   general-absence source lands.
7. **Explore trends** (existing feature, collapsed) — metric picker +
   multi-year line chart + table, with an added England-average
   reference line and a COVID-gap annotation.

**Metric exposure model (three tiers).** No measure from the current
page is lost; they surface at three levels of prominence:
- **Tier 1 — headline strips (always visible):** RWM expected,
  reading/writing/maths expected, RWM higher standard.
- **Tier 2 — "More measures" expansion inside Academics:** GPS and
  science expected % (science labelled teacher-assessed), average
  scaled scores (reading/maths/GPS, same dot-strip grammar showing
  the 100–120 window of the 80–120 scale, widening below 100, with
  the England tick) — one tap/click away, same visual language.
  *Post-v1:* gender split and absence (see §4.6).
- **Tier 3 — Explore trends:** the full grouped catalogue (the
  current page's ~40 metrics, including equity and school-context
  measures, and the GCSE set for secondary phase) drives the
  year-by-year chart and table via the grouped metric picker.
The tier assignment is a content decision per phase (secondary:
Attainment 8, Progress 8 banding, grade 5+ English & maths as tier 1;
EBacc and subject entries as tier 2).

Finance (per-pupil spend) is deliberately deferred: low parent value,
risk of misreading. Revisit later.

**Mobile (design target — mobile first):** the desktop grid is the
adaptation, not the other way round. On mobile the layout goes
*measure-first*: each row is one measure with all schools listed under
it (colour dot + short name + value + chip), so comparison never
requires horizontal swiping between school cards. A sticky horizontal
school-chip bar keeps identity and add/remove available while
scrolling. Dot strips already read measure-first and carry over
unchanged. The trend chart scrolls horizontally inside its container.

## 5. Data strategy — existing dataset only

Constraint (agreed 2026-07-11): use only data already in marts plus
fields already present in the `raw` schema extracts we pull today.
No new external sources.

**Gaps in the mockup, resolved within this constraint:**

| Mockup element | Resolution |
|---|---|
| England average for disadvantaged pupils | Compute from our own data: `stg_ees_ks2` already pivots the Disadvantaged breakdown per school; aggregate it (weighted by eligible pupils) into `fact_ks2_national_averages` or compute in the API. Label it "England average (state schools)". |
| England context for FSM / EAL / SEN chips | Compute dataset-wide medians per phase, same pattern as `/api/national-averages` does for KS4. |
| "Much larger than average" size label | Dataset median pupils-on-roll per phase. |
| Ofsted link | We don't have deep links to the latest report, so always link to the school's Ofsted provider page, `https://reports.ofsted.gov.uk/provider/21/{urn}`, derived from URN (label it "the school's Ofsted page", not "the report"). |

**Raw fields we already pull but don't store — promote to marts (one
dbt/pipeline PR, no tap changes):**

- `raw.ees_admissions`: 2nd/3rd preference applications and offers,
  total-preference counts, cross-LA applications and offers → richer
  "Getting a place" (e.g. "offers reached 2nd-choice families",
  competition from outside the borough).
- `raw.ees_ks2_attainment`: progress-measure confidence intervals and
  "working towards" % → lets the Above/Average/Below progress chips be
  statistically honest (band by CI overlap with 0, mirroring DfE
  methodology) instead of thresholding the point estimate.
- `raw.ees_ks4_performance` / `ees_ks4_info`: `progress8_banding`
  (DfE's own plain-English "well above average … well below average"
  label — exactly the chip we want for secondary), EBacc entry/APS,
  grade-5+ English & maths, `attainment8_diffn`/`progress8_diffn`
  (disadvantage gaps) → the secondary-phase version of the Academics
  section.
- `raw.ees_census`: young-carer % and the ethnicity breakdown →
  optional "Who goes there" enrichment; hold for a later iteration
  (presentation needs care), but the data requires no new extract.
- `raw.ofsted_inspections` / tap-uk-ofsted: the `rc_*` report-card
  columns exist in staging/marts but are stubbed `null` — the tap has a
  TODO to map the report-card column names from the Ofsted MI file
  (same monthly extract we already download; inspections from Nov 2025
  onward carry them). This is the one promotion that needs a small tap
  schema addition, and it's a prerequisite for the new-framework Ofsted
  display above.

Explicitly out (not in any current extract): school-level phonics,
workforce/teacher data, per-school attendance beyond the KS2 test-day
absence fields, Ofsted report-card documents themselves.

## 6. API changes

Extend `GET /api/compare` response per URN with the same supplementary
blocks the detail endpoint already builds (`get_supplementary_data`):
`ofsted`, `census`, `admissions` (+ `admissions_history`), `deprivation`,
plus a top-level `national_averages` block for the latest year. Reuse the
existing function; no new tables. Response stays backward-compatible
(additive fields only). Add derived helper fields server-side or compute
chips client-side from `national_averages` (client-side preferred — no
schema churn).

## 7. Accessibility & comprehension devices

- Verdict chips are text + colour + position (never colour alone).
- Every acronym has a tooltip using existing `MetricTooltip`.
- "How to read this" one-liner at the top of each section.
- Chart palette: coral `#e07256`, teal `#00949b`, purple `#8664c9`
  (validated: lightness band, chroma, CVD separation, contrast — the
  current `--chart-2/-4` tokens fail chroma/contrast checks and should
  be nudged to these).
- Numbers rounded to whole percents; England tick labelled on first use.

## 8. Expert-review requirements

An adversarial review by an education-data expert (full findings in
`2026-07-11-compare-screen-expert-review.md`) was applied to the
mockups on 2026-07-12. The following are binding requirements for
implementation, beyond what the mockups can show:

1. **Chart truthfulness:** KS2 tests were cancelled 2019/20–2020/21
   only. **2021/22 school-level figures are a permanent source gap** —
   DfE stated it would not publish KS2 2021/22 in performance tables
   (verified 2026-07-12 against EES, the CSP download service, and
   DfE release notes; see `# TASK 6 VERIFICATION` in
   `pipeline/scripts/diagnose_compare_gaps.py`). The chart's England-
   only 2021/22 point with broken school lines is therefore the
   correct permanent rendering; copy should say "DfE didn't publish
   school-level figures for 2021/22", not "not in our dataset yet".
   The 2015/16 national figure and the GPS/science/scaled-score
   England averages ARE loadable (mapping already correct; refreshed
   raw extract backfills them). Never render missing years as if time
   were continuous.
2. **Report-card summaries** count graded areas only — safeguarding is
   a separate binary flag, never included in rating counts.
3. **Admissions:** use the real preference-breakdown fields from
   `raw.ees_admissions`; never derive "lower-preference offers" as
   places − first-preference offers. Frame total applications as
   "named on N forms" (any rank), lead with first-preference success,
   and standardise at-a-glance chips on that one metric. Explain the
   equal-preference rule; caveat offers vs final intake (waiting
   lists/appeals); condition "distance decides" on the school's actual
   oversubscription criteria where we have the admissions-policy field.
4. **Ofsted:** overall grades ended September 2024 (report cards from
   November 2025); the interim regime must be renderable. Distinguish
   graded (s5) vs ungraded (s8) inspections and surface carried-forward
   grades as such; "we don't hold the detail" is a statement about our
   dataset, never about the inspection. Verify every scale/area label
   against Ofsted's final published toolkit before launch (e.g. "Needs
   attention" vs "Attention needed"; "Personal development and
   well-being" vs the identically-named legacy judgement). Check
   whether a school's latest inspection is merely its latest *graded*
   one. Confirm Early years provision subgrades flow through the
   pipeline for schools with nurseries.
5. **Subgroup honesty:** disadvantaged-pupil percentages carry cohort
   sizes and follow the DfE suppression rule (≤5 pupils suppressed);
   state the rule verbatim in the footer.
6. **Benchmark provenance:** official DfE figures and
   dataset-computed benchmarks must be labelled distinctly and
   consistently everywhere (a computed median is a "benchmark",
   not an "England average").
7. **Copy details:** "Latest Ofsted inspection" (not "Ofsted rating");
   "EHC plans"; SEN-support benchmark ≈14%; high SEN share may
   indicate resourced provision (say so neutrally); "at or above
   capacity" rather than "full" (capacity data is often stale);
   disambiguate Ofsted's "Expected standard" from the KS2 measure;
   give official terms ("first preference") alongside plain English.
   Writing has no "higher standard" — its TA outcome is "greater
   depth (GDS)"; never list writing under a higher-standard group.
   Science and writing are teacher-assessed and must be labelled as
   such (no KS2 science test since 2009). House style for benchmark
   provenance: official DfE figures say "England average"; computed
   figures say "state-school average (computed from our dataset)" —
   applied to every chip, tooltip, header note and section intro.
   EAL uses the census wording: first language known or believed to
   be other than English. If IDACI ships, caveat that it describes
   pupils' home neighbourhoods, not the school.

## 9. Rollout

1. **PR 1 (backend):** extend `/api/compare` + tests.
2. **PR 2 (frontend):** new compare layout behind the existing route;
   e2e journey updated in the same PR (promotion gate).
3. **Fix separately:** missing third series on the current chart.

## 10. Open questions for review

- Max schools: keep 10 in API but cap visible columns at 4 with scroll?
- Should distance-from-home appear when the user searched by postcode
  (data exists via `dim_location`)?
- Keep finance out of v1? (Recommended: yes, out.)