Group Research in Special Education

Abstract

Special education research is an interdisciplinary field requiring a broad range of methodologies. This paper focuses on group research, which can be distinguished from single-subject design in several important ways: (1) group research involves the extensive and limited observations of many subjects rather than the intensive observations of a small number of subjects; (2) group research emphasizes the average performance of groups of subjects rather than the process of change itself; (3) results are evaluated through statistical analyses rather than visual interpretation of individual subject data; and (4) results are more broadly generalizable across subjects, settings, and occasions. The distinction between experimental and nonexperimental strategies is addressed within the context of group strategies. Four classes (Cook & Campbell, 1979) of threats to valid inference which may be controlled by experimental designs are identified: internal validity, statistical conclusion validity, external validity, and construct validity of causes and effects.