fix(admissions): correct first_preference_offer_pct in dbt staging

The staging model was mapping EES column ``proportion_1stprefs_v_totaloffers``
straight onto ``first_preference_offer_pct``. That raw column is not a
percentage — it is a ratio of first-preference applications to total offers
(an oversubscription indicator, >1 means oversubscribed), so OLQH rendered
as "1%" when the true first-choice success rate is 27/42 = 64%.

The frontend display code is not at fault and is not patched here —
data-quality issues must be fixed at the source.

- stg_ees_admissions: compute ``first_preference_offer_pct`` as
  ``100 * number_1st_preference_offers / times_put_as_1st_preference`` —
  of families who listed this school first, the % that received an offer
  (0–100). Guard against divide-by-zero.
- stg_ees_admissions: expose the legitimate EES ratio as the new column
  ``oversubscription_ratio`` (1st-preference applications per place) for
  future use, clearly named.
- fact_admissions, FactAdmissions model, data_loader: propagate the new
  ``oversubscription_ratio`` column.
- SchoolAdmissions type: document both columns inline.
- buildSchoolSummary: reword the oversubscription clause so it reads
  sensibly across the whole 0–100 range (no more "just 64%").
- Hero chip subtitle: clearer phrasing "X% of first-choice applicants
  offered a place".

Requires a dbt run of stg_ees_admissions and fact_admissions on deploy
so the new column materialises.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/data_loader.py

@@ -414,6 +414,7 @@ def get_supplementary_data(db: Session, urn: int) -> dict:
             "first_preference_applications": a.first_preference_applications,
             "first_preference_offers": a.first_preference_offers,
             "first_preference_offer_pct": a.first_preference_offer_pct,
+            "oversubscription_ratio": a.oversubscription_ratio,
             "oversubscribed": a.oversubscribed,
         }
         if a

backend/models.py

@@ -184,6 +184,7 @@ class FactAdmissions(Base):
     first_preference_applications = Column(Integer)
     first_preference_offers = Column(Integer)
     first_preference_offer_pct = Column(Float)
+    oversubscription_ratio = Column(Float)
     oversubscribed = Column(Boolean)
     admissions_policy = Column(String(100))
 

nextjs-app/components/SchoolDetailView.tsx

@@ -226,7 +226,7 @@ export function SchoolDetailView({
               <div className={styles.heroChipTitle}>Oversubscribed</div>
               <div className={styles.heroChipSub}>
                 {admissions.first_preference_offer_pct != null
-                  ? `${Math.round(admissions.first_preference_offer_pct)}% got first choice`
+                  ? `${Math.round(admissions.first_preference_offer_pct)}% of first-choice applicants offered a place`
                   : 'More applicants than places'}
               </div>
             </div>

nextjs-app/lib/types.ts

@@ -134,7 +134,10 @@ export interface SchoolAdmissions {
   total_applications: number | null;
   first_preference_applications?: number | null;
   first_preference_offers?: number | null;
+  /** Of families who listed this school as 1st preference, the % that received an offer (0–100). */
   first_preference_offer_pct: number | null;
+  /** 1st-preference applications per place offered (>1 means oversubscribed). */
+  oversubscription_ratio?: number | null;
   oversubscribed: boolean | null;
 }
 

nextjs-app/lib/utils.ts

@@ -557,11 +557,12 @@ export function buildSchoolSummary(
   // Admissions clause
   if (admissions?.oversubscribed) {
     if (admissions.first_preference_offer_pct != null) {
+      const pct = Math.round(admissions.first_preference_offer_pct);
       parts.push(
-        `heavily oversubscribed — just ${Math.round(admissions.first_preference_offer_pct)}% of applicants get a first-choice offer`,
+        `oversubscribed — ${pct}% of first-choice applicants are offered a place`,
       );
     } else {
-      parts.push('heavily oversubscribed');
+      parts.push('oversubscribed');
     }
   } else if (admissions?.first_preference_offer_pct != null && admissions.first_preference_offer_pct >= 90) {
     parts.push('most families get their first-choice offer');

pipeline/transform/models/marts/fact_admissions.sql

@@ -9,6 +9,7 @@ select
     first_preference_applications,
     first_preference_offers,
     first_preference_offer_pct,
+    oversubscription_ratio,
     oversubscribed,
     admissions_policy
 from {{ ref('stg_ees_admissions') }}

pipeline/transform/models/staging/stg_ees_admissions.sql

@@ -29,7 +29,25 @@ renamed as (
         {{ safe_numeric('times_put_as_1st_preference') }}::integer as first_preference_applications,
 
         -- Proportions
-        {{ safe_numeric('proportion_1stprefs_v_totaloffers') }} as first_preference_offer_pct,
+        -- first_preference_offer_pct: of families who listed this school FIRST,
+        -- the percentage that received an offer. 0–100 scale.
+        -- The raw EES column `proportion_1stprefs_v_totaloffers` stores a
+        -- different, misleading figure (first-preference applications divided
+        -- by total offers, i.e. an oversubscription ratio) — do not use it.
+        case
+            when {{ safe_numeric('times_put_as_1st_preference') }} > 0
+                then 100.0
+                     * {{ safe_numeric('number_1st_preference_offers') }}
+                     / {{ safe_numeric('times_put_as_1st_preference') }}
+        end as first_preference_offer_pct,
+
+        -- Oversubscription ratio: 1st-preference applications per place offered.
+        -- >1 means the school is oversubscribed on first preferences.
+        case
+            when {{ safe_numeric('total_number_places_offered') }} > 0
+                then {{ safe_numeric('times_put_as_1st_preference') }}::numeric
+                     / {{ safe_numeric('total_number_places_offered') }}
+        end as oversubscription_ratio,
 
         -- Derived: oversubscribed if 1st-preference applications > places offered
         -- Use already-cast columns to avoid repeating the regex expression