Parent, teacher, and child ratings of problem behaviors of youngsters with serious emotional disturbances.

Method effects as a source of construct invalidity were evaluated for parent, teacher, and child ratings of problem behaviors among children and adolescents with serious emotional disturbances. A multitrait-multimethod (MTMM) matrix consisting of 4 types of problems (i.e., internalizing, thought, attention, and externalizing), rated by 3 sources, was analyzed using confirmatory factor analysis. Subjects were 489 youngsters, ages 8 to 18 years (M = 13.86), who were classified as having serious emotional disturbances. Results indicated large method effects for each rater. These effects may represent either measurement artifact, true situational differences, or a combination of both. Modeling method effects is necessary to obtain unbiased estimates of the relationships between children's multiple problems and other variables