Controlling for inequality in neuropsychological assessment: using Crawford and Howell’s (1998) single-case methodology with norms from demographically homogeneous groups of South Africans

Abstract

The practice of neuropsychological assessment in South Africa is complicated by the lack of norms that are representative of clients’ educational and linguistic experiences. In an attempt to address this challenge, we argue that Crawford and Howell’s Single-Case Methodology in Neuropsychology is a good option for the neuropsychological investigation of cases that are not well represented by the available norms. This research design and inferential statistical method compares the scores of one case to the performance of a carefully matched sample of modest size. In order that practitioners and researchers might use this methodology, we provide a set of norms for South Africans with specific demographic profiles on a range of well-researched and commonly used neuropsychological tests. We provide an illustrative case study to demonstrate the application of Crawford and Howell’s Single-Case Methodology, which shows how the selection of an appropriately matched norm (control) group is an effective way to reduce test biases for individuals who are not represented by the original test norms.