Field and Natural Experiments

Planning, property, health

21 & 26 May 2021

The heightened ‘security zone’ function of gated communities: Natural experiment evidence from the COVID-19 pandemic

Lecturer in Real Estate Finance,

Department of Land Economy,

University of Cambridge

The ongoing COVID-19 pandemic has left strong imprint on many aspects of urban life. Gated communities (GCs) in China are less commonly perceived as a negative and segregated urban form compared to other contexts, owing to its wide variety and relative openness. Yet, the enhanced security zone function and the popularity of GCs, along with the heightened segregation and exclusion effects, are mostly likely to emerge in post-pandemic urban China because of the perceived effectiveness of GCs in preventing health risks by excluding outsiders during the pandemic. Drawing on empirical data from Beijing and utilising a difference-in-difference strategy, this research presents strong evidence for a surging ‘security zone’ effect of GCs during the pandemic. Given that rigid pandemic control measures were organised at the community level, a large-scale household survey in Beijing suggests that residents commonly recognise the effectiveness of GCs in security control and show strong preference for GCs over open communities after the pandemic. The heightened ‘security zone’ function of GCs has shown a significant impact on the housing market, evidenced by an increase of 2% in the housing prices for GCs, compared with that of open communities. The rising popularity of GCs is also evidenced in a significant increase of properties viewing by potential homebuyers and smaller price discounts in actual transactions in gated communities vis-à-vis open communities. This study provides timely and fresh insights into the changing meaning of GCs in post-pandemic China

Postdoc Fellow, Department of Urban Planning and Design,

The University of Hong Kong

Does a natural environment enhance the efficacy of mindfulness-based stress reduction (MBSR)?

This study investigated whether the impacts of a commonly used wellbeing intervention, Mindfulness-Based Stress Reduction (MBSR), are enhanced when combined with the benefits of exposure to a natural environment. Participants (n = 99) were randomly assigned to a weekly one-hour MBSR in one of three different environments (i.e. natural outdoor, built outdoor and indoor environments) over a six-week period. Participants’ wellbeing outcomes and nature connectedness were measured at baseline, during the intervention and at one-week and one-month follow up. The results show that the mental health and wellbeing outcomes of MBSR are greater when it carried out in a natural outdoor environment compared with indoor or built environments. Moreover, participants in the natural outdoor environment showed sustained improvements even after one month from completion of the intervention. This study supports the potential value of natural environments as settings for the enhancement of health care delivery and therapeutic interventions.

Dean and Chair Professor,

Faculty of Architecture. The University of Hong Kong

Event 1: 10:00am -12:00pm UK time / 5:00-7:00pm HK time, 21 May 2021

Ling Li, Wayne Xinwei Wan, Shenjing He

Eun Yeong Choe, Anna Jorgensen, David Sheffield

Event 2: 10:00am -12:00pm UK time/5:00-7:00pm HK time,  

21 May, 2021

ZOOM: XXX

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Dr Christina Li

An artefactual experiment on the performance of agglomeration bonuses in conservation auctions: Lessons from the field

The incorporation of an agglomeration bonus payment to encourage spatial coordination in auction mechanisms to allocate Payments for Ecosystem Services (PES) contracts has been explored as a promising innovation that could enhance the effectiveness of PES schemes. Yet, actual empirical evidence on the performance of this particular design feature is scant, and almost exclusively derived from laboratory experiments using student subjects. This study reports results from a lab-in-the field (artefactual) experimental auction allocating PES contracts with and without agglomeration bonus payments using actual forest holders as subjects. We find that, in an auction setting, the agglomeration bonus induces a bidding pattern in favour of contiguous conservation. Moreover, the agglomeration bonus has the potential to ‘pay its own way’, since subjects tend to bid less in anticipation of receiving bonus payments when their neighbours are also successful in the auction. In addition, our results lend strong support for the cost-effectiveness of conservation auctions relative to fixed-rate payment schemes.  

Department of Land Economy

University of Cambridge

Dr Christina Li

Department of Land Economy

University of Cambridge

Event 2: 12:30-2:30pm UK time / 7:30-9:30pm HK time, 26 May 2021

An artefactual experiment on the performance of agglomeration bonuses in conservation auctions: Lessons from the field

Zhaoyang Liu, Jintao Xu, Xiaojun Yang, Qin Tu, Nick Hanley, Andreas Kontoleon

The incorporation of an agglomeration bonus payment to encourage spatial coordination in auction mechanisms to allocate Payments for Ecosystem Services (PES) contracts has been explored as a promising innovation that could enhance the effectiveness of PES schemes. Yet, actual empirical evidence on the performance of this particular design feature is scant, and almost exclusively derived from laboratory experiments using student subjects. This study reports results from a lab-in-the field (artefactual) experimental auction allocating PES contracts with and without agglomeration bonus payments using actual forest holders as subjects. We find that, in an auction setting, the agglomeration bonus induces a bidding pattern in favour of contiguous conservation. Moreover, the agglomeration bonus has the potential to ‘pay its own way’, since subjects tend to bid less in anticipation of receiving bonus payments when their neighbours are also successful in the auction. In addition, our results lend strong support for the cost-effectiveness of conservation auctions relative to fixed-rate payment schemes.  

Professor of Environmental Economics and Public Policy,

Department of Land Economy,

University of Cambridge

Assistant Professor, Department of Urban Planning and Design,

Director of Urban Analytics and Interventions Research Lab,

The University of Hong Kong

Natural experiments in built environment and health studies: Enhancing the design-based approach by urban planning and design knowledge

Guibo Sun, Eun Yeong Choe, Chris Webster

There is a large body of studies on health effects of built environments. Few, however, are able to establish causal relations. In part, this is because researching built environment's health impact by changing built environment experimentally, is impracticable. As a result, there is a growing interest in natural experiments. In the context of the recent reconnection of urban planning and public health, we consider how “naturally occurring” built environment changes brought by urban planning and design practices can be structured as health interventions. Without randomisation in intervention exposure as a randomised control experiment does, we argue that the challenge in natural experiments lies in validating confounding effects approximate random distribution between treatment and control groups. We review high-profile natural experiments and find that experimental credentials could be established imprecisely. This motivates us to build a conceptual model to demonstrate that, by distinguishing between a design-based approach and a post-design statistical model-based approach, how the substantive knowledge in urban planning and design practices can help design stronger natural experiments using built environment changes to infer causality of their health effects.

Discussant: Dr Zhaoyang Liu

University Lecturer in Applied Economics,

Department of Land Economy, University of Cambridge

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