Descriptive research is designed to document the factors that describe characteristics, behaviors and conditions of individuals and groups. For example, researchers have used this approach to describe a sample of individuals with spinal cord injuries with respect to gender, age, and cause and severity of injury to see whether these properties were similar to those described in the past.1 Descriptive studies have documented the biomechanical parameters of wheelchair propulsion,2 and the clinical characteristics of stroke.3 As our diagram of the continuum of research shows, descriptive and exploratory elements are commonly combined, depending on how the investigator conceptualizes the research question.
Descriptive studies document the nature of existing phenomena and describe how variables change over time. They will generally be structured around a set of guiding questions or research objectives to generate data or characterize a situation of interest. Often this information can be used as a basis for formulation of research hypotheses that can be tested using exploratory or experimental techniques. The descriptive data supply the foundation for classifying individuals, for identifying relevant variables, and for asking new research questions.
Descriptive studies may involve prospective or retrospective data collection, and may be designed using longitudinal or cross-sectional methods (see Chapter 13). Surveys and secondary analysis of clinical databases are often used as sources of data for descriptive analysis. Several types of research can be categorized as descriptive, including developmental research, normative research, qualitative research and case studies. The purpose of this chapter is to describe these approaches.
Concepts of human development, whether they are related to cognition, perceptual-motor control, communication, physiological change, or psychological processes, are important elements of a clinical knowledge base. Valid interpretation of clinical outcomes depends on our ability to develop a clear picture of those we treat, their characteristics and performance expectations under different conditions. Developmental research involves the description of developmental change and the sequencing of behaviors in people over time. Developmental studies have contributed to the theoretical foundations of clinical practice in many ways. For example, the classic descriptive studies of Gesell and Amatruda4 and McGraw5 provide the basis for much of the research on sequencing of motor development in infants and children. Erikson's studies of life span development have contributed to an understanding of psychological growth through old age.6
Developmental studies can be characterized by the method used to document change. The longitudinal method involves collecting data over an extended period, to document behaviors as they vary over time. Because the same individuals are tested throughout the study, personal characteristics remain relatively constant, and differences observed over time can be interpreted as developmental change. With the cross-sectional method, the researcher studies various developmental levels (usually age levels) within a particular cohort of subjects and describes differences among those levels as they exist at a single point in ...