Click on the following links. Please note these will open in a new window.

Journal Article Link 9.1: Matowe, L. K., Leister, C. A., Crivera, C., & Korth-Bradley, J. M. (2003). Interrupted time series analysis in clinical research. The Annals of Pharmacotherapy, 37(7), 1110–1116.

Abstract: To demonstrate the usefulness of interrupted time series analysis in clinical trial design. Methods: A safety data set of electrocardiographic (ECG) information was simulated from actual data that had been collected in a Phase I study. Simulated data on 18 healthy volunteers based on a study performed in a contract research facility were collected based on single doses of an experimental medication that may affect ECG parameters. Serial ECGs were collected before and during treatment with the experimental medication. Data from seven real subjects receiving placebo were used to simulate the pretreatment phase of time series; data from 18 real subjects receiving active treatment were used to simulate the treatment phase of the time series. Visual inspection of data was performed, followed by tests for trend, seasonality, and autocorrelation by use of SAS. Results: There was no evidence of trend, seasonality, or autocorrelation. In 11 of 18 simulated individuals, statistically significant changes in QTc intervals were observed following treatment with the experimental medication. A significant time of day and treatment interaction was observed in 4 simulated patients. Conclusions: Interrupted time series analysis techniques offer an additional tool for the study of clinical situations in which patients must act as their own controls and where serial data can be collected at evenly distributed intervals.

1. In your own words, what is the purpose of time series design?
2. Why was this design used in the study?
3. What are the advantages and disadvantages of this research design?
4. Could another quasi-experimental research design be used? Which one?

Journal Article Link 9.2: McDougall, D., Hawkins, J., Brady, M., & Jenkins, A. (2006). Recent innovations in the changing criterion design: Implications for research and practice in special education. The Journal of Special Education, 40(1), 2–15.

Abstract: This article illustrates (a) two recent innovations in the changing criterion research design, (b) how these innovations apply to research and practice in special education, and (c) how clinical needs influence design features of the changing criterion design. The first innovation, the range-bound changing criterion, is a very simple variation of the classic changing criterion design. The classic version uses a single criterion for each stepwise intervention phase, whereas the range-bound version uses a range criterion—that is, an upper and lower limit for each intervention phase. The second innovation, the distributed criterion, combines elements of the changing criterion, multiple-baseline, and ABAB designs. It is well suited to contexts where students must multitask—that is, allocate, prioritize, and adjust time and effort to complete multiple tasks in response to changing environmental demands. These two innovations expand options available to researchers who use single-case research designs to investigate questions of interest in special education.

1. What is a single-case research design?
2. Why was this type of research design used?
3. How could this study be made into a quasi-experimental design with a larger sample?