One-shot Case Study
The one-shot case study involves the measurement of an identified "outcome" after a treatment or program has been implemented. However, there are no measures taken or available for comparison (i.e., status before the program, or outcome of a comparison or control group). Without a comparison measure, there is no means for inferring that the "outcome" was actually influenced by the treatment or program.
US Environmental Protection Agency. (2007). Program Evaluation Glossary. Office of the Administrator/Office of Policy/Office of Strategic Environmental Management/Evaluation Support Division.