Tenements were viewed as plague houses in nineteenth century industrial cities such as Glasgow, London, New York and Berlin. Replacing the tenements with social housing was seen as a key marker of social progress in the late 19th and 20th centuries. But as austerity budgets have spread across national and local governments in the 21st century, public expenditure on social housing, like other collective services, is not necessarily protected. Yet success in breaking the link between poor housing and health inequalities critically depends on retaining a social role for housing.1

How can public health researchers make the case that good quality housing is an upstream determinant of health? Good quality housing for low-income people is a public good which is under-provided by the private market—the market ignores negative spillovers, such as infectious disease, as well as social spillovers, such as community instability affecting education outcomes. Attaining positive health and social outcomes therefore requires some public funding to be sustainable. The social housing system frequently selects sick people as priority tenants; this suggests that evaluating the impact of social housing requires a robust methodological design.

Lawson and colleagues took the opportunity to evaluate the Scottish Government's progressive broad healthy public policy approach and make substantial investments in new social housing. Scottish housing associations approached their clientele, but only 46% of those approached agreed to participate in this study.2 Using a matched sample rather than randomisation inevitably resulted in a sample that was not matched on some key variables, such as age, …