Prima Pagina ARIPS
Analyses of Social Issues and Public Policy, 2001, pp. 95­127


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The Prevention of Homelessness Revisited
Marybeth Shinn*, New York University, Jim Baumohl, Bryn Mawr College, Kim Hopper, Nathan S. Kline Institute
Conceptual and methodological problems plague efforts to prevent homelessness. Attempts to identify individuals at risk are inefficient, targeting many people who will not become homeless for each person who will. Such interventions may do useful things for needy people, but evidence that they prevent homelessness is scant. Subsidized housing, with or without supportive services, has ended homelessness for families and played a key role in ending it for people with serious mental illnesses. Other risk factors may be less important once housing is secured. But programs that allocate scarce housing may simply reallocate homelessness, determining who goes to the head of the line for housing, not shortening the line itself. We recommend reorienting homelessness prevention from work with identified at-risk persons to efforts to increase the supply of affordable housing and sustainable sources of livelihood nationwide or in targeted communities.
Anyone who has passed a person sleeping in a doorway, seen a family with belongings heaped in a shopping cart, observed makeshift dwellings under a bridge, or visited a shelter where strangers lie warily on adjacent beds is likely to have thought that surely such scenes could be prevented. In our view, homelessness in the United States could be avoided, for the most part. And yet we are notsanguine about the prospects. A lack of resources is not the only obstacle, though itis the most formidable. In addition, current efforts to prevent homelessness are based largely on questionable premises. Tributes to their effectiveness are statements of faith that cannot withstand scientific scrutiny. (Most such efforts douseful things for needy people but have only a marginal impact on the prevention ofhomelessness.) In view of persisting conceptual and methodological quandariesand in light of the limited empirical evidence available, we recommend that homelessness prevention be reoriented from efforts to work with identified at-risk persons to projects aimed at increasing the supply of affordable housing and sustainable sources of livelihood.

The Logic of Prevention

Simply put, to prevent means to keep something that would have happened from happening in fact. At a minimum, the logic of prevention requires that we define clearly what is to be prevented, specify the intervention(s), and establish a causal (or at least correlational) connection between intervention and avoidance of the undesirable phenomenon. Other things equal, the more narrow the prevention goal, the more clearly specified the intervention, and the more rigorous the design of evaluation, the easier the task of determining effectiveness. The prototypical example is of a discrete disease entity (say, polio), preventable by vaccination (a simple, easily standardized intervention), where effectiveness can be demonstrated by comparing outcomes in vaccinated and unvaccinated samples.

Alas, most unwanted phenomena are more like suicide than polio: they are ambiguously defined, multiply caused, questionably responsive to interventions, and difficult to assess. Moreover, most interventions are complex and difficult to standardize and may reshape the outcome of interest. (A "right to shelter" provision may cause some people living in crowded or deficient housing to presentthemselves at shelters, thus redefining their circumstances and the nature of whatwe call homelessness.) Only in the most strained metaphors are social interventions anything like vaccinations.

Note, too, that prevention involves predicting the future. To determinewhether an intervention is successful, we must know the likelihood that the unwanted will occur, so that we may compare this likelihood with the actual outcome following intervention. (Not everyone will get even an easily transmissibledisease; if it is rare, few will be affected.) Thus, to allocate resources efficiently or ration scarce ones, prevention programs often target subjects who have been "exposed" (in the language of disease) or who are, by some theoretically plausible or empirically determined criteria, "at risk" of being affected. A simple,..........>>>>>>
**Correspondence concerning this article should be sent to Beth Shinn, Department of Psychology,New York University, 6 Washington Place, Room 552, New York, NY 10003 [ An earlier, more detailed version of this article was presented at the Housing and Urban Development/Health and Human Services National Symposium on Homelessness Research: What Works and published in a volume of conference proceedings (Shinn & Baumohl, 1999). Although we acknowledge that some of them disagree with our conclusions, we thank James Hoben, Diane Hughes,David Krantz, Eric Lindblom, Julia Littell, Philip Mangano, Ruth Schwartz, Edward Seidman, Hirokazu Yoshikawa, and the organizers of the symposium for their insightful comments on earlier versions of this article.