Data and methodology
Data and methodology
Every number in a BuyDNA report is traceable to a source and a date. Where a source has nothing for your property, the report says "data unavailable" rather than filling the space. This page explains the whole method, including what it cannot do.
Where the data comes from
Sources are ranked in tiers. When two sources disagree, the higher tier wins and the conflict is recorded in your report rather than hidden.
| Tier | Source | What it provides | Refresh |
|---|---|---|---|
| Tier 1 — Government | NSW Planning Portal (zoning, overlays, land use) | Zoning, heritage and planning constraints | Checked daily; served from the authority's current layer |
| Tier 1 — Government | NSW SIX Maps / Spatial Services (cadastre, geocoding) | Parcel identity, lot and plan, coordinates | Live query per property |
| Tier 1 — Government | NSW flood and bushfire hazard mapping | Flood and bushfire exposure at the parcel | Live query per property |
| Tier 1 — Government | NSW infrastructure and corridor reservations | Reserved land, road and rail corridors nearby | Daily catalogue refresh |
| Tier 1 — Government | ACARA My School | School identity, sector and level near a property | Annual dataset; refreshed when published |
| Tier 1 — Government | Transport for NSW (GTFS) | Distance to stations, stops and interchanges | Weekly feed refresh |
| Tier 1 — Government | Australian Bureau of Statistics | SA2 boundaries, income and household composition | Census and quarterly releases |
| Tier 2 — Licensed | PropRadar (Pro) | Attributes, sale history, comparable sales, valuations, rental evidence, suburb medians, market cycle | Per-property live query, cached six hours for suburb series |
| Tier 3 — Listing | The listing page you paste | Asking price or guide, campaign type, agent claims | Read at the moment you submit it |
Hazard and planning mapping is currently connected for New South Wales. For properties in other states, those sections report the gap explicitly instead of guessing.
How a report is built
- 01
Identify the property
We resolve your link or address to a single parcel — lot, plan and coordinates. If we can't be sure which property you mean, we ask you to confirm rather than assume.
- 02
Retrieve evidence
Each connected source is queried for that parcel and its suburb. Every value is stored with its source, its as-at date and a confidence weight.
- 03
Check for conflicts
Where sources disagree on a material fact (land size, sale price, hazard status), the conflict is recorded. Serious conflicts stop the report.
- 04
Calculate
Deterministic maths only: comparable selection and adjustment, price per square metre, Fair Value, yield, offer positions, completeness.
- 05
Write the analysis
Specialist AI modules explain the calculated evidence. They are given only the retrieved evidence — no outside knowledge, no browsing.
- 06
Critic pass
A second model checks every written claim against the evidence list and strips anything unsupported. Removals are logged.
- 07
Release or hold
Reports below our evidence threshold are not sold — they either fail with a reason, or go to human review first.
Scores and weightings
Seven DNA signals are calculated for a property, each 0–100 and each a weighted average of named inputs. Together they feed the BuyDNA Score. A signal is only calculated when enough of its inputs exist; otherwise it reports "insufficient data" rather than scoring the gaps as neutral. Every report lists each signal's inputs, the weight applied, and which inputs were missing.
ValueDNA
How strongly the available evidence supports the property's value and its asking-price position: comparable sales, price per square metre, automated valuation and listing position.
GrowthDNA
What the available longer-term market and supply/demand fundamentals indicate: observed suburb growth, market heat, approvals and months of stock.
RentDNA
What the available rental evidence indicates: rental comparables, gross yield, vacancy and rent movement.
RiskDNA
What identified property, planning and environmental risk evidence exists: flood and bushfire mapping, heritage and planning constraints, market volatility. Higher score = fewer identified risk concerns based on the available evidence.
LocationDNA
What the available evidence indicates about location and accessibility: schools, transport, health and retail amenity, walkability, distance to the CBD and area characteristics.
LivingDNA
How well the property and location work from an owner-occupier and liveability perspective, using available evidence and, where present, your Buyer Brief.
DealDNA
What the available pricing, comparable-sale, market and negotiation evidence indicates about the buying position: days on market, stock levels and sold-versus-asking behaviour.
BuyDNA Score
A weighted blend of the seven signals — not an average. Identified risk evidence can cap the overall score regardless of how strongly the other signals read.
The Fair Value method
1. Select comparables
Verified sales in a widening radius and time window, filtered to like-for-like property type. Each comparable is scored for quality by distance, recency and attribute similarity, and the report shows why each one was included.
2. Adjust for differences
A regression across the comparable set estimates the local value of bedrooms, bathrooms, land and internal area, and each sale is normalised toward the subject property. The fit statistic is published; a weak fit reduces confidence rather than being hidden.
3. Blend the independent estimates
The adjusted comparable range, the licensed automated valuation and the provider forecast are weighted by their observed reliability. Every weight and its source appear in the report, and a wide spread widens the published range.
4. Offer positions
Opening, target and upper-evidence-limit figures come from the Fair Value range plus observable market pressure (days on market, stock levels, sold-versus-asking). We do not estimate the probability a vendor accepts — no dataset we hold would make that honest.
What the confidence levels mean
High
Several independent sources agree, the evidence is recent, and the comparable set is strong. Figures are still estimates.
Applied when: 70%+ data completeness and no unresolved source conflicts
Medium
The core evidence exists but is thinner — fewer comparables, older sales, or one source only.
Applied when: 45–70% completeness, or a strong set with one gap
Low
We can see something, but not enough to lean on. Treat it as a prompt to investigate, not a conclusion.
Applied when: Under 45% completeness, or a conflict we could not resolve
Data unavailable
We could not source it. We show this instead of estimating, every time.
Applied when: No verified value from any connected source
Confidence is capped by data completeness: a report built on 60% of the evidence we expect can never present a high-confidence conclusion, however tidy the numbers look.
What BuyDNA will not claim
- Predict what a specific property will sell for, or whether a vendor will accept an offer.
- Fill a gap with a suburb average and present it as a figure for your property.
- Give legal, tax or financial advice, or replace a solicitor, conveyancer or building inspector.
- Claim a hazard is absent when the mapping for that state is not connected — we say so instead.
- Use a paid tier to unlock 'better' data. Paid tiers unlock more analysis of the same evidence.
Privacy and security
Your searches are yours
Reports, saved properties, offers and your Buyer Brief are readable only by your account. Access is enforced in the database, not just in the interface.
Documents stay private
Contracts and reports you upload are stored in private storage that only your account can read, and you can delete them at any time.
Calculators run locally
Every figure you type into the buying calculators is computed in your browser and never sent to us.
We don't sell your data
We do not sell or share your personal information with agents, brokers or advertisers.
Deleting your account
Deleting your account removes your profile, saved properties, offers, documents and briefs.
Card details
Payments are handled by our payment provider. We never see or store your card number.
Corrections, complaints and refunds
If a figure is wrong
Tell us which report and which figure. We re-run the retrieval, record the correction against the report with the reason, and reissue it. Corrections are versioned, so you can see what changed and why.
Refunds
If a paid report turns out to be materially wrong on a sourced fact, or we could not source enough evidence to deliver the sections you paid for, we refund it. A $39 report credited toward a Buyer Pass within 7 days is credited, not refunded twice.
Subscriptions
Investor Pro is monthly and cancels any time from your account page; access runs to the end of the period you have paid for. A Buyer Pass is a fixed 30-day window, not a recurring subscription.
BuyDNA provides property research, software tools and general information based on available data and user inputs. It does not provide legal, financial, tax, credit, valuation, structural or personal investment advice. Data may be incomplete, delayed or inaccurate. Users should independently verify important information and obtain advice from appropriately qualified professionals before making a property decision. Questions about the method? Run a free snapshot and every figure will show its source and date.