APT · EVIDENCE TIMELINE · NOTE 14

Normalize area before comparing two sale records

A transaction-field audit shows why raw prices for 59.9㎡ and 84.9㎡ homes cannot be ranked without an area-normalized view.

REPRODUCIBLE WORK

Follow the evidence in the order it becomes usable.

01

Read source fields

Transaction amount + exclusive-use area

Two differently sized homes
02

Normalize A

₩720M ÷ 59.9㎡

About ₩12.02M/㎡
03

Normalize B

₩930M ÷ 84.9㎡

About ₩10.95M/㎡
04

Interpret

A normalized rate − B normalized rate

A is about 9.8% higher per ㎡ despite the lower total price

SOURCE SNAPSHOT

Anchor the evidence to its source and time.

INPUT AND EVIDENCE LEDGER

Keep the snapshot attached to its origin.

FieldValueOrigin
Record A₩720M / 59.9㎡Controlled fixture using official fields
Record B₩930M / 84.9㎡Controlled fixture using official fields
Area fieldExclusive-use areaMOLIT transaction schema
ComparisonWon per exclusive-use ㎡APT transformation

DECISION READING

What survives the timeline check.

Total price answers an affordability question; price per square metre answers a different comparability question. APT should show both and still avoid treating units with different floor, orientation, condition, or date as identical.

SENSITIVITY

Where the chain can go stale.

  • Using gross floor area instead of exclusive-use area would change the denominator.
  • Renovation, floor, view, and transaction month can dominate the normalized difference.
  • Narrower area buckets improve comparability but reduce sample size.

BOUNDARIES

Do not extend the timestamp into a promise.

  • The pair is a calculation fixture, not a named-property valuation.
  • Per-square-metre normalization does not make two units fully comparable.
  • Only reported transactions, not listings, belong in this evidence layer.

HUMAN ACCOUNTABILITY + AI USE RECORD

The owner is accountable; the technical checks were AI-assisted.

The TOOOLBOX site owner authorized the publication scope and remains the correction contact. AI assistance was used for drafting, implementation, arithmetic recomputation, and source-link checks. This record does not claim line-by-line human fact-checking or licensed professional review.

Record ID
TB-APT-14-20260902
Owner role
TOOOLBOX site owner and developer
Technical check date
2026-09-02
Human fact-check
No separate human fact-check recorded
AI use
Drafting, code, arithmetic, and link checks
Correction channel
Public contact page
  1. Verified the official interface exposes price and exclusive-area fields.
  2. Recomputed both normalized values and the percentage difference.
  3. Added non-area comparability limits before publication.

MORE APT DECISION NOTES

Test the result yourself.

This note preserves a dated calculation. Change the inputs in the live workspace, or compare another evidence pattern below. Live source availability and results can differ from the dated example.