This document discusses various single subject and quasi-experimental research designs used in social science research, including reversal, multiple baseline, changing criterion, interrupted time series, and correlational designs. It notes key aspects of single subject designs like establishing patterns of responding, shifting conditions, and replicating effects across individuals. Quasi-experimental designs trade internal validity for external validity. Archival, time series, and ex-post facto designs can establish relationships but not causation. Naturalistic observation alone cannot prove causation but can generate hypotheses for further testing.