Why should we study the impacts of local affordable housing policies? One key reason is to help planners and policymakers design better programs that will meet their communities’ needs. But what if research studies seem to come to different conclusions? How can you figure out what research to rely on?
In the report Separating Fact from Fiction to Design Effective Inclusionary Housing Programsprepared for the National Housing Conference (NHC), I reviewed the studies of the impacts of inclusionary zoning policies and found that the most highly-regarded empirical studies show that these programs can produce affordable housing and do not lead to significant declines in overall housing production or to increases in market-rate prices.
So, how are critics of inclusionary zoning able to point to research to support their claim that inclusionary zoning is bad for housing markets? Not all research is of equal quality and some of the key studies cited by critics have some serious design flaws. When evaluating the quality of research on housing programs, it is good to ask a few questions about how the researchers set up the study:
When evaluating a local housing program, did the researchers simply compare outcomes (e.g. housing production, home prices) in a locality before and after the program was implemented? That is not usually the best approach. Rigorous evaluations use a research design that i) compare outcomes in localities with inclusionary housing programs to similar localities without inclusionary requirements, and ii) account for other factors that could influence housing market outcomes.
Did the research study examine program impacts in a place that is very different from the community you are working in? For planning and policymaking purposes, it is a good idea not to generalize findings from a research study conducted in one particular place (e.g. a high-cost city with rising home prices) and assume those findings would be true in a place with very different characteristics (e.g. a rural area with a stagnant housing market).
Was the program implemented as stated in the policy documents and/or ordinance? In some cases, researchers conduct an evaluation of a program without first ensuring that the policy was actually administered as it was intended. A process evaluation—that is, an assessment of how, or even if, the program was implemented—is a helpful first step to understand whether the change in outcomes that are measured can actually be attributed to the policy.
Evaluation research is an important tool for local affordable housing planners and policymakers. Indeed, “evidence-based policymaking” is increasingly part of crafting public policy at all levels of government. We need to be sure to review research with an understanding of what makes a good research study, and to avoid cherry-picking studies that support our point of view.
