2018国际房价负担能力调查报告（英文版）_65页_2mb

14th Annual Demographia International Housing Affordability Survey: 2018 Summary

Core Content

This document presents the findings of the 14th Annual Demographia International Housing Affordability Survey for the third quarter of 2017, focusing on housing affordability in the United Kingdom and comparing it to Demographia's methodology. The authors, Felipe Carozzi, Paul Cheshire, and Christian Hilber from the London School of Economics, replicate Demographia's median multiple (MM) measure and explore its limitations and variations.

Main Points

1. Replication of Demographia's Median Multiple

• The authors successfully replicated Demographia's median multiples for UK housing markets using similar data sources and methods.
• The correlation between the two sets of MM measures is 0.92, indicating a strong alignment.
• The study uses Travel to Work Areas (TTWAs) as functional urban regions, which are more closely aligned with actual housing markets than administrative regions.

2. Definition of Housing Markets

• Housing markets are spatially bounded and are influenced by job locations.
• Administrative regions, such as those used by Eurostat, often do not align well with real housing market areas.
• The use of TTWAs allows for more accurate analysis of housing affordability within urban functional areas.

3. Impact of House Size on Affordability

• Adjusting for house size had a minimal effect on affordability measures in the UK.
• The correlation between the original MM and the size-adjusted MM is 0.98, suggesting strong relationship.
• While larger cities tend to have smaller houses, the demand for space increases with income, which limits the effect of size adjustments on affordability.

4. Affordability Across Income Groups

• Affordability varies significantly across income percentiles.
• Poorer households face much higher housing costs relative to their income, even though they buy smaller, cheaper houses.
• The affordability gap is most pronounced in the least affordable cities, such as London.
• Adjusting for taxes and national insurance significantly reduces the affordability gap, especially in high-cost areas.

5. Tax and Benefit Considerations

• Demographia's MM is based on gross income, not net (after-tax) income.
• Adjusting for taxes and benefits reduces the affordability gap, especially for the poorest and richest households in high-cost areas.
• In some cities, after-tax affordability even reverses the pre-tax affordability gap.

Key Findings

• Administrative regions can obscure significant differences in housing affordability within them.
• TTWAs offer a more accurate representation of housing markets and their affordability.
• House size adjustments have a limited effect on affordability measures in the UK.
• Income distribution reveals that housing is most unaffordable for the poorest groups.
• Taxes and benefits play a crucial role in shaping affordability, particularly in high-cost cities.

Conclusions

• The study confirms that Demographia's MM is a useful proxy for housing affordability, though it has limitations.
• Adjustments for house size and income distribution provide more nuanced insights into affordability.
• The housing affordability crisis is linked to urban containment policies and land use restrictions.
• The authors emphasize the importance of focusing on actual urban housing markets rather than administrative regions for accurate analysis.

Acknowledgements and Authors

• The authors acknowledge the efforts of Xiaolun Yu in data collection and merging datasets.
• They are affiliated with the Department of Geography and Environment at the London School of Economics and the Centre for Economic Performance.
• The introduction includes perspectives from Wendell Cox and Hugh Pavletich, highlighting the global implications of housing affordability and policy responses in New Zealand.

Highlights from Previous Introductions

• Oliver Hartwich (New Zealand, 2016): Emphasized the need to address extreme housing prices and the role of land supply in affordability.
• Senato: Mentioned the impact of land supply on housing affordability, with a focus on the United States and California's high poverty rates due to housing costs.

Summary Table (Key MM Values)

Final Remarks

• The study underscores the importance of accurate regional definitions and consideration of income distribution in assessing housing affordability.
• It also highlights the human and economic costs of housing unaffordability, particularly in areas with restrictive land use policies.
• The authors suggest that future research should explore whether these findings apply to other countries.