Academic journal article American Annals of the Deaf

Single-Case Design Research: Building the Evidence-Base in the Field of Education of Deaf and Hard of Hearing Students

Academic journal article American Annals of the Deaf

Single-Case Design Research: Building the Evidence-Base in the Field of Education of Deaf and Hard of Hearing Students

Article excerpt

Single-Case Design Research

The term evidence-based practices (EBPs) refers to educational programs or instructional procedures that have been determined to produce positive results. Both the Individuals With Disabilities Education Improvement Act of 2004 (the reauthorizing legislation for IDEA, the Individuals With Disabilities Education Act of 1990) and the No Child Left Behind Act of 2001 (NCLB) require educators to use EBPs. Using EBPs to guide decision making can help improve the quality of services provided to students by effecting a shift to a culture in which judgments are valued and are guided by research data that can be inspected by a broad audience, rather than the opinions of individual experts (Camine, 2000).

In order to determine that an educational program or instructional procedure produces positive results, researchers seek to establish a functional relationship between the independent variable (the conditions that cause change) and the dependent variable (the behavior that is changed). Experimental research is regarded as the most effective way to examine the effectiveness of an educational pro- gram or practice (Council on Exceptional Children, 2014). Group experimental studies, which are considered the "gold standard" for determining EBPs, require relatively large samples and random assignment to treatment and control groups. The effectiveness of a program or practice is examined through comparisons between the outcomes of the two groups. By providing the intervention to only one of the groups, the researchers can then draw conclusions about whether a program or practice causes the desired changes in participants' outcomes (Tankersley, Harjusola-Webb, & Landrum, 2008).

For several reasons, group experimental studies of effective programs and practices are difficult to conduct with deaf and hard of hearing (DHH) students. First, DHH students constitute a low-incidence population. (The U.S. Department of Education reports that 0.296-1.0% of students receive services under IDEA; Snyder & Dillow, 2013; U.S. Department of Education, National Center for Education Statistics, 2013.) Therefore, it is challenging to identify a sufficiently large sample to enable detection of the results of an intervention, or to obtain a representative sample to ensure generalizability of the results. Second, the heterogeneity of the population makes it difficult to create equivalent comparison groups on variables such as age at onset of hearing loss, use of assistive hearing technology, mode of communication, or degree of hearing loss, and confounding effects such as teacher communication ability or level of parent/guardian involvement. As a result, most experimental studies with DHH students have low numbers of participants, highly variable groups, and samples of convenience rather than design, making it more likely that Type II errors may occur (i.e., failure to reject a false null hypothesis).

The lack of quality experimental research to guide practice can be frustrating for teachers and administrators working with DHH students. A paucity of experimental and quasi-experimental research addressing educational practices that have been tested and demonstrated as being effective with DHH students currently exists, according to a variety of researchers (e.g., Beal-Alvarez & Cannon, 2014; Cannon & Guardino, 2012; Easterbrooks & Stephenson, 2006; Luckner & Cooke, 2010; Luckner & Handley, 2008; Luckner, Sebald, Cooney, Young, & Muir, 2005/2006; Luckner & Urbach, 2011; Schirmer, & McGough, 2005; Spencer & Marschark, 2010). Consequently, it is appropriate for the field of education of DHH students to embrace other designs that allow researchers to draw conclusions about whether a program or practice causes desired changes.

A research design that accounts for the individual needs of DHH students is single-case design (SCD; Horner et al., 2005; Kazdin, 2011; Kennedy, 2005). …

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