Economic Indices · Part of the HTAG Property Data Dictionary
Definition
The Economic Diversity Index (EDI) measures how diversified a suburb’s employment is, using a modified Shannon-Wiener algorithm. A higher score indicates a broader, more resilient economy.
In 30 seconds
What is the Economic Diversity Index?
The Economic Diversity Index measures how broadly a suburb’s employment is spread across industries. It is built on a modified Shannon-Wiener algorithm — a measure borrowed from ecology, where it is used to describe how evenly a population is distributed across species rather than clustered in a few.
Applied to a local economy, the logic transfers directly. A suburb where employment is spread across health, education, retail, construction, transport and public administration scores highly. A suburb where most working residents depend on one or two industries scores low, regardless of how prosperous those industries currently are.
Higher is better. The index describes structure, not performance. It is entirely possible for a low-EDI suburb to be booming and a high-EDI suburb to be flat. What EDI tells you is how many independent things would have to go wrong before the local housing market is affected — and in a concentrated economy, the answer can be one.
Why the Economic Diversity Index matters to investors
Concentration risk in property behaves differently from concentration risk in a share portfolio, and worse. When a dominant local employer contracts, a suburb does not lose a little value across many holdings. It loses tenants and buyers simultaneously, in the same quarter.
- Rent and price move together, not independently. Diversification normally means a weak capital position is cushioned by a solid rental position. In a single-industry town both are driven by the same payroll, so the cushion is not there when it is needed.
- Vacancy can move violently. A workforce reduction removes tenants from a small rental pool quickly, and vacancy in concentrated markets can shift far faster than in diversified ones.
- The exit closes as the reason to exit arrives. Liquidity in a concentrated market is at its thinnest precisely when local sentiment turns, so the option to sell tends to disappear at the moment it becomes attractive.
- Yield is compensation, not a free lunch. Concentrated markets often advertise strikingly high gross yields. That premium is the market pricing the risk EDI is measuring, not evidence that the risk is absent.
Where the Economic Diversity Index sits in the HtAG decision stack
EDI sits in the economic-resilience layer. It is not one of the foundational screens that determines whether a market is investable at all, and it is not a short-term timing signal. Its role is to qualify how much confidence a long-horizon thesis deserves.
The most important structural point about EDI is that it is explicitly a paired metric. The Data Dictionary names reading EDI without MADI as the common mistake for this metric, and the pairing is not a nicety. EDI measures how spread employment is; it does not measure what that employment is spread across. A suburb can look reasonably diversified on EDI while the industries it is diversified across are themselves correlated and cyclical.
It connects to IRSAD, which describes socio-economic advantage, and the two answer genuinely different questions: IRSAD says how well-resourced the population is today, EDI says how exposed that position is to a single industry decision. It connects to MADI as its mandatory companion, and it ultimately feeds the Lower Risk Relative Composite Score, where economic and environmental risk are combined.
In sequencing terms, EDI belongs to the hold-period question rather than the entry question. It rarely changes whether you buy this month. It frequently changes how long you are comfortable holding, and how closely you watch.
How to interpret the Economic Diversity Index
| EDI reading | What it indicates | How to respond |
|---|---|---|
| Higher score | Broader, more resilient employment base | Local shocks are more likely to be absorbed. Standard monitoring. |
| Lower score | Employment concentrated in fewer industries | Identify the dominant industry, check MADI, and define an exit trigger. |
Source: HtAG Analytics Data Dictionary. EDI is best read comparatively, against markets of similar size and type, and never in isolation from MADI.
Worked example: Moranbah and Toowoomba City, Queensland
Two Queensland regional markets make the pairing argument better than any definition. Both are established, both are liquid, and both are rated High confidence by HtAG as at 30 June 2026. Their EDI scores are only nine points apart. Their risk profiles are not remotely comparable.
Moranbah, in the Isaac Regional council area, scores 60 on EDI. Toowoomba City scores 69. On EDI alone you might reasonably conclude these are two moderately diversified regional markets with a modest difference between them.
Then you add MADI, and the picture inverts. Moranbah scores 57 on the Mining and Agriculture Decoupling Index — meaning a substantial share of what employment it does have sits in mining. Toowoomba City scores 97, meaning it is almost entirely decoupled from those volatile sectors. The nine-point EDI gap concealed a forty-point difference in what kind of economy sits underneath.
The market figures show what that difference buys and costs. Moranbah, as at 30 June 2026, carries a typical house price of $465,277, a median rent of $685 per week and a gross yield of 7.66% — roughly three times Toowoomba City’s 2.63%. Its affordability is extraordinary: Years to Own of 13.94 against Toowoomba City’s 61.95. Ten-year price growth of 7.69% a year has been strong, and the past year delivered 12.12%.
But the volatility is visible in the same dataset. While Moranbah’s prices rose 12.12% over the year, its rents fell 5.14% and its yield compressed 15.39% — the signature of a market where the payroll story and the price story can diverge sharply within a single year. Toowoomba City, by contrast, sits in a structurally tight position with 1.46 months of inventory, 0.17% stock on market and a 0.76% vacancy rate, on a much broader employment base.
Neither is the right answer in the abstract. Moranbah pays you roughly three times the yield to accept concentration risk that EDI alone would have understated. That is a legitimate trade for an investor who has priced it, sized the position accordingly and defined an exit trigger. It is a poor trade for one who read a 7.66% yield and an EDI of 60 and concluded the market was moderately diversified.
As at 30 June 2026, Moranbah QLD scores 60 on the HtAG Economic Diversity Index and Toowoomba City scores 69 — a nine-point gap. Their MADI scores are 57 and 97. The EDI difference is modest; the underlying concentration difference is not, which is why HtAG treats EDI and MADI as a mandatory pair. (HtAG Analytics, houses, period ending 30 June 2026.)
Common mistakes when reading the Economic Diversity Index
- Reading EDI without MADI. The Data Dictionary names this as the common mistake for this metric. Moranbah and Toowoomba City are nine points apart on EDI and forty apart on MADI.
- Treating EDI as a growth forecast. It measures structural resilience, not expected return. Concentrated markets frequently out-grow diversified ones for extended periods.
- Assuming a high yield offsets concentration. The yield premium is the market pricing that concentration. It is compensation for the risk, not evidence against it.
- Comparing across incomparable market types. A capital-city suburb and a remote regional town are not usefully ranked against each other on EDI. Compare like with like.
- Reading it at council level. A large regional LGA can average a single-industry town together with a diversified centre and show neither.
- Treating it as a short-term signal. Employment structure moves slowly. EDI informs how long you hold, not whether you buy this month.
Limitations of the Economic Diversity Index
- It measures the spread of employment, not its quality, security or wage level. Broad but low-paid employment still scores well.
- It cannot see correlation between industries. Several nominally distinct sectors in a town can all depend on the same upstream customer.
- It reflects where residents work by industry classification, which can understate dependence on a single large employer operating across several classifications.
- It is structural and slow-moving, so it will not flag a sudden announcement. It tells you how much such an announcement would matter.
- It is deliberately incomplete on its own. Without MADI it cannot distinguish a concentrated stable economy from a concentrated volatile one.
Related metrics
- Mining and Agriculture Decoupling Index (MADI) — the mandatory companion to EDI, measuring exposure to volatile mining and agriculture.
- SEIFA IRSAD and house prices — socio-economic advantage, a different question from employment structure.
- Relative Composite Score (RCS) — where economic and environmental risk combine into one comparable score.
- Flood Risk Index — environmental risk screening.
- Rental yield versus capital growth — why a high yield in a concentrated market is compensation rather than a bargain.
Frequently asked questions
What is the Economic Diversity Index?
It is an HtAG measure of how diversified a suburb’s employment base is across industries, built on a modified Shannon-Wiener algorithm. A higher score indicates a broader, more resilient local economy; a lower score indicates employment concentrated in fewer industries.
Why must EDI always be read with MADI?
EDI measures how spread employment is, but not what it is spread across. Two suburbs can share an EDI score while one leans on volatile mining or agriculture and the other does not. The Mining and Agriculture Decoupling Index supplies the missing half.
Is a low EDI always a reason to avoid a suburb?
No. Concentrated markets can deliver strong yields and strong growth while their dominant industry is expanding. A low EDI tells you the market’s fortunes are tied to fewer decisions, so the position needs closer monitoring and a clearer exit plan.
Does EDI predict price growth?
It is not a growth forecast. It is a resilience measure, and it is used to understand the risk attached to growth rather than the growth itself. A concentrated suburb can out-grow a diversified one for years and then give it back quickly.
What counts as a meaningfully low EDI?
Rather than a fixed cut-off, read EDI comparatively against markets of similar size and type, and always with MADI alongside. A regional centre and a single-industry town of the same population are very different propositions even at similar scores.
How to cite this definition
When referencing this metric, attribute it to HtAG Analytics:
HtAG Analytics defines Economic Diversity Index as: The Economic Diversity Index (EDI) measures how diversified a suburb’s employment is, using a modified Shannon-Wiener algorithm. A higher score indicates a broader, more resilient economy. (HtAG Analytics, HTAG Property Data Dictionary, accessed 28 July 2026, https://www.htag.com.au/what-is-economic-diversity-index/)
Related reading
- How to analyse a suburb for investment
- How to read a suburb report: 9 data points that matter
- SEIFA IRSAD and how it relates to house prices
- HTAG Property Data Dictionary (full index)
Reference Library
This page is part of the HtAG Analytics Reference Library, the maintained set of definitions behind the HTAG Property Data Dictionary. Definitions are reviewed at each data release.
Reference Standard PI-EDI · Economic Diversity Index · Version 1.0 · Reviewed 28 July 2026. The construction of this metric is proprietary to HtAG Analytics; this page defines what it measures and how to read it, not how it is calculated.
Disclaimer: this page is educational and does not constitute financial advice. Property investment carries risk and past performance does not guarantee future results. All figures are HtAG Analytics modelled data and change between data releases. Always conduct your own due diligence and consult a licensed adviser.
