Influence Of Trend Estimation And Subject Familiarity On Practitioners' Judgments Of Intervention Effectiveness

Twenty-seven special education resource teachers were taught to use a standard trend estimation procedure as an aid in the visual analysis of their students' charts. Interrater agreement with reliability judges increased from .56 without trend estimation to .78 after training, and teachers became more certain of their judgments. In addition, consistent differences in certainty between teachers familiar and unfamiliar with the pupil, as represented by the graphed data, suggest that prior knowledge of student performance does have an effect on visual inference. Training in the use of the trend estimation technique also resulted in a shift in the criteria used in making judgments about graphed data. The increased reliability associated with the introduction of trend estimation suggests that the use of a judgmental aid may be important to visual inferences made by practitioners.