Scoring Methodology
How Address Twin calculates suburb scores
Principle
Every score on Address Twin is the weighted average of 8 independent component scores, each calculated from a single official data source. There are no black-box proprietary models. Every component score, its weight, its source, and its data currency date are visible on the scorecard.
Score Components
Affordability
Landgate property transactionsMedian sale price (houses, last 12 months). Higher score = more affordable relative to Perth metro median (~$750k). Score of 50 = at metro median.
Bushfire Risk
DFES Bushfire Prone Area mappingDominant DFES risk classification for a point within the suburb. Extreme=5, Very High=15, High=35, Medium=60, Low=80, No zone=95.
Crime Rate
WA Police Force crime statisticsTotal recorded offences per 1,000 residents (last 12 months). WA average ~60/1,000. Score of 50 = at state average. Higher score = lower rate.
Transit Access
Transperth GTFSTrain stops within 800m (weighted more heavily) and bus stops within 400m. Train presence = score 60+, bus only = score 30-75, none = 10.
Schools
ACARA My SchoolBased on ICSEA (Index of Community Socio-Educational Advantage) of nearest government primary school within 2km. ICSEA mean = 1,000, SD ~100.
Air Quality
EPA WA Air Quality Monitoring NetworkAQI from nearest active monitoring station. Kwinana industrial corridor flag overrides with score of 20. Good (<50 AQI)=90, Fair=65, Poor=40, Very poor=15.
Socioeconomic
ABS Census 2021 SEIFASEIFA IRSAD decile (1=most disadvantaged, 10=most advantaged). Note: 2021 Census data is current as of August 2021 and may not reflect recent demographic changes.
Contaminated Sites
EPA WA Contaminated Sites RegisterCount and proximity of EPA-listed contaminated sites within 3km. None=95, Nearest >2km=70, Nearest 500m–2km=45, Nearest <500m=20.
Weighting Profiles
The overall score is the sum of (component score × weight) divided by total weight. Weights sum to 1.0 within each profile.
| Component | Family | Car-light commuter | Budget maximiser | Resilience-first |
|---|---|---|---|---|
| property Value | 15% | 15% | 35% | 10% |
| bushfire Risk | 15% | 5% | 10% | 30% |
| crime Rate | 20% | 15% | 15% | 15% |
| transit Access | 10% | 35% | 15% | 10% |
| school Quality | 25% | 10% | 10% | 5% |
| air Quality | 5% | 10% | 5% | 15% |
| demographics | 5% | 5% | 5% | 5% |
| contamination | 5% | 5% | 5% | 10% |
Limitations
- Scores are point-in-time snapshots based on the most recent available data for each source.
- ABS Census data is from 2021 and is particularly outdated for fast-growing suburbs.
- School quality proxied by ICSEA only — does not include NAPLAN results or other performance indicators.
- Transit scores are based on stop proximity, not service frequency or reliability.
- Air quality monitoring coverage is sparse in outer Perth suburbs.
- No score accounts for lifestyle factors (café density, beach proximity, community feel) that many buyers value highly.