Social work practice at all system levels involves action leading to behav- ioral or cul tural change. The primary role of social work research is to provide knowledge that contributes to such professional action. vVhile descriptive research about human and cultural conditions, as discussed elsc·where in this volume, can be valuable for guiding professional action,

knowing how to most effectively support change is critical for practice. A central question for social work research, therefore, is “what works” in practice, what works to address what goals and issues, with what populations, under what contextual conditions. While descriptive research ca11 suggest hypotheses, the only way to really determ ine howweU any form of practice works is to test it, under the most rigorous conditions possible.

Experimen tal research is therefore critical for advancing social work practice. Unfon·tunately, only a small proportion of social work research is experimental (Thyer, 200 I). Experimental research is of two types, group experiments (e.g., randomized clinical trials [RCTs]) and single-system research (SSR, also commonly referred to as single case resealfch, N of 1 research, or interrupted time-series experiments). Single-system experi- mental research, however, has often been underemphasized in social work, in part because of limited understanding of the logic of natural science among social scientists and wcial workers.

SSR is experimental research; its purpose, as noted by Horner and colleagues (2005), is “to document causal, or functional, relationships between independent and dependent variables” (p. 166). The methodology has been used with all system levels-micro, mezzo, and macro-m aking it widely appliCable for studying social work concerns. For example, Moore, Delaney, and Dixon (2007) studied ways to enhance quality of life for quite impaired patients with Alzheimer’s disease using single-system methods and were able to both individualize interven tions and produce generalizable knowledge from their study in ways that perhaps no other research strategy could equal. In another example, Serna, Schumaker, Sherman, and Sheldon (1991) worked to improve family interactions in families with preteen and teenage children. The first several interventions they attempted (interventions that are common in social work practice) fa iled to produce changes that generalized to homes. Single-system procedures, however, allowed them to rigorously and sequentially test multiple approaches until an adequately powerful intervention strategy was refi ned. (Note that Lhis would be impossible using group methods without under- mining the rigor of the study.)



Turning to larger systems, single-system designs can be used, for example, to examine the relative effects of different sets of organizational and community contex.’tS on the effectiveness of school violence prevention efforts (Mattaini, 2006). Furthermore, Jason, Braciszewski, Olson, and Ferrari (2005) used multiple baseline single-system methods to test the impact of policy changes on the rate of opening mutual help recovery homes for substance abusers across entire states. Embry and colleagues (2007) used a similar design to test the impact of a statewide intervention to reduce sales of tobacco to m inors.

Although single-system methods are widely used for practice monitoring in social work, research and monitoring are different endeavors with different purposes. This chapter focuses on the utility of SSR for knowledge building. Readers interested in 1 he use of single-system methods for practice monitoring are likely to find Bloom, Fischer, and Orme (2006) and Nugent, Sieppert, and Hudson (2001 ) particularly helpful.

Understanding Single-System Research

Single-system experimental research relies on natural science methodologies, while much of the rest of social work research, including a good deal of group experimental research, emphasizes social science methods. The differences are real and substantive. In 1993, Johnston and Pennypacker noted,

The natural sciences have spawned technologies that have dramatically transformed the h uman culture, and the pace of technological development only seems to increase. The social sciences have yet to offer a single well-developed technology that has had a broad impact on daily life. (p. 6)

There is lillie evidence that this s ituation has changed. The reasons involve both meth- ous and philosophies of science. Critically, however, analysis is central in most natural sci- ences and is best achieved through the direct manipulation of variables and observation of the impact of those manipulations over a period of time. As one expert noted, the heart or SSR is demonstrating influence by “mak[ing] things go up and down” under precisely specified conditions (J. Moore, personal communication, 1998). Such analysis is often best done one case at a time.