Comparative Time-Series Design
Comparative time-series design is a quasi-experimental design that tracks some outcome of interest for periods before and after program implementation for both the treatment group as well as a non-randomly selected comparison group. Because comparison and treatment groups are not randomly selected, alternate explanations due to prior differences between groups continue to be a threat.
US Environmental Protection Agency. (2007). Program Evaluation Glossary. Office of the Administrator/Office of Policy/Office of Strategic Environmental Management/Evaluation Support Division.