We are pleased to bring you this special issue of Brain Impairment on quantitative data analysis, an area of increasing complexity and sophistication. In planning the special issue, our intention was to bring together a set of articles covering diverse and topical areas in the field, with the idea of having the volume serve as a ‘go-to’ resource. The special issue is aimed at researchers, clinicians engaged in research, and advanced students all of whom may have passing familiarity with a particular data analytic technique, but wish to know more about it and how to apply it. Accordingly, our aim is to equip the reader with concrete, hands-on information that can be applied in the day-to-day world of research. The authors of the articles comprising the special issue, each of whom is an expert in his/her field, were charged with the task of writing a practical guide and providing worked examples to illustrate the application of their selected technique/s. The papers in the special issue cover three domains: the single-case method, between-groups design, and psychometric aspects of instrument development.