Family of research and evaluation designs characterized by the systematic repeated measurement of client outcomes and regular, frequent, predesignated intervals under different conditions, baseline and intervention, and the evaluation of outcomes over time, and under different conditions in order to monitor client progress, identify intervention fax, and more generally, learn when, why, how, and the extent to which client change occurs. Also known as single–subject design, single–system designs, and N=1 designs, or sometimes time-series or interrupted time-series designs.
