macrohard

All candidate causes

Housing cost and land-supply constraint

Restrictive land supply, slow servicing of land and high building costs make housing expensive relative to incomes. The hypothesis is that high housing cost pushes citizens, especially people aged 20-39, to leave, and loads demand onto public provision. The official record documents the cost pathway, not a housing-to-emigration pathway.

Open 0 of 4 support, 1 against; partly supported needs two more.

Timing Contradicts Does the cause move before the symptom?
Departures should rise after price-to-income rises; they did not. New Zealand's price-to-income index peaked at 136.1 in 2021 and fell 24% by 2025, while citizen departures rose from 52,036 (2022) to 67,352 (2024). Over 2004-2025, excluding 2020-21, departures and the index are negatively correlated (r = -0.34).103.53 / 136.13 = 0.761, a 24% fall, 2021 to 2025. Pearson r, n = 20: departures against the index -0.34 (same year), -0.11 (one-year lag), +0.09 (two-year lag); departures to Australia -0.58.OECD, Analytical house prices: price-to-income index (HPI_YDH), 2000-2025; Stats NZ, Net migration loss to Australia in 2025 (2026)
Distribution Mixed Is the symptom worse where the cause is stronger?
Stats NZ publishes NZ-citizen departures by region, assigned from the address nearest the departure date. Year to Feb 2024, departures per 1,000 residents ran from 5.2 (West Coast) to 17.8 (Auckland). Across 16 regions the link to house price to income is weak and not significant (r = +0.27). Tenure is not published.Rate = NZ-citizen departures / 2023 Census residents x 1,000: Auckland 29,505 / 1,656,486 = 17.8; West Coast 174 / 33,390 = 5.2. Pearson r = +0.27 (p = 0.32), Spearman +0.25 (p = 0.34), n = 16.Stats NZ, Estimated migration by direction, citizenship and NZ area (Infoshare, Feb 2024) (secondary); Stats NZ, 2023 Census usually resident population counts by region; HUD, Local Housing Statistics Dashboard (median house price to income, Jun 2023)
Peers Mixed Do comparable countries with the same cause show the same symptom?
Price-to-income also rose steeply in Canada, Australia and Denmark from 2000 to 2021 without comparable citizen exit. Ireland's emigration peaked in 2012 as its house prices collapsed, rose again in 2022-24 with prices steady, then eased in 2025-26 as its price-to-income ratio rose: a weak fit at best.Price-to-income 2021 / 2000: NZ 2.24; Canada 2.06; Australia 1.66; Denmark 1.39; Ireland 0.92. Ireland emigration per 1,000: 18.1 (2012), 13.0 (2024), 11.3 (2026) = 62.5 ÷ 5,525.6 × 1,000; price-to-income 112.7 (2024), 118.0 (2025).OECD, Analytical house prices: price-to-income index (HPI_YDH), 2000-2025; Central Statistics Office Ireland, PEA15 Annual Population Change
Mechanism Mixed Does an official review document the pathway?
Official reviews document the cost pathway: land supply, servicing and building costs. None links housing cost to emigration. The Productivity Commission (2015) records councils rationing trunk infrastructure to stay within debt limits, so housing cost is partly downstream of asset funding.Productivity Commission, Housing affordability inquiry: final report (2012); Productivity Commission, Using land for housing: final report (2015); OECD, Economic Surveys: New Zealand 2019, ch. 3 housing policy

What would settle it: Link departures to prior tenure and region in the Stats NZ Integrated Data Infrastructure, and test whether renters and residents of high price-to-income regions leave at higher rates, controlling for age, occupation and the NZ-Australia unemployment gap.

tested · the causes as data

Cite Housing cost and land-supply constraint

macrohard.nz, “Housing cost and land-supply constraint”, The Hollowing Index, tested 2026-09-30. https://macrohard.nz/causes/housing-cost