**Health Policy & Behavioral Sciences Resources (PHPB): About Study Designs

Systematic Review

A summary of the clinical literature. A systematic review is a critical assessment and evaluation of all research studies that address a particular clinical issue. The researchers use an organized method of locating, assembling, and evaluating a body of literature on a particular topic using a set of specific criteria. A systematic review typically includes a description of the findings of the collection of research studies. The systematic review may also include a quantitative pooling of data, called a meta-analysis.  

Example:
Wanchai, A., Armer, J. M., & Stewart, B. R. (2010). Complementary and Alternative Medicine Use Among Women With Breast Cancer: A Systematic Review. Clinical Journal of Oncology Nursing, 14(4).

Adapted from Study Designs; in NICHSR Introduction to Health Services Research: a Self-Study Course

Randomized Controlled Trial

A controlled clinical trial that randomly (by chance) assigns participants to two or more groups. There are various methods to randomize study participants to their groups.  

Example:

Barrett, B., Hayney, M. S., Muller, D., Rakel, D., Ward, A., Obasi, C. N., ... & West, R. (2012). Meditation or exercise for preventing acute respiratory infection: a randomized controlled trial. The Annals of Family Medicine, 10(4), 337-346.

Adapted from Study Designs; in NICHSR Introduction to Health Services Research: a Self-Study Course

Cohort Study (Prospective Observational Study)

A clinical research study in which people who presently have a certain condition or receive a particular treatment are followed over time and compared with another group of people who are not affected by the condition.

Example:

Croucher, R., Shanbhag, S., Dahiya, M., Kassim, S., Csikar, J., & Ross, L. (2012). Smokeless tobacco cessation in South Asian communities: a multi‐centre prospective cohort study. Addiction, 107, 45-52.

Adapted from Study Designs; in NICHSR Introduction to Health Services Research: a Self-Study Course

Case-control Study

Case-control studies begin with the outcomes and do not follow people over time. Researchers choose people with a particular result (the cases) and interview the groups or check their records to ascertain what different experiences they had. They compare the odds of having an experience with the outcome to the odds of having an experience without the outcome.

Example:

Persaud, N., Coleman, E., Zwolakowski, D., Lauwers, B., & Cass, D. (2012). Nonuse of bicycle helmets and risk of fatal head injury: a proportional mortality, case–control study. CMAJ, 184(17), E921-E923.

Adapted from Study Designs; in NICHSR Introduction to Health Services Research: a Self-Study Course

Cross-sectional study

The observation of a defined population at a single point in time or time interval. Exposure and outcome are determined simultaneously.

Example:

Steiner, M. J., Skinner, A. C., & Perrin, E. M. (2011). Fasting might not be necessary before lipid screening: a nationally representative cross-sectional study. Pediatrics, 128(3), 463-470.

Adapted from Study Designs; in NICHSR Introduction to Health Services Research: a Self-Study Course

Case Reports & Series

A report on a series of patients with an outcome of interest. No control group is involved.

Example:

Lattanzi, J. B., Campbell, S. L., Dole, R. L., & Palombaro, K. M. (2011). Students mentoring students in a service-learning clinical supervision experience: an educational case report. Physical Therapy, 91(10), 1513-1524.

Adapted from Study Designs; in NICHSR Introduction to Health Services Research: a Self-Study Course

Ideas, Editorials, Opinions

Put forth by experts in the field.

Example:

Koop, C. E. (2006). Health and health care for the 21st century: for all the people. American Journal of Public Health 96(12):2090-2.

Adapted from Study Designs; in NICHSR Introduction to Health Services Research: a Self-Study Course

Animal Research Studies

Studies conducted using animal subjects.

Example:

Schulz, C., Paulus, K., Jöhren, O., & Lehnert, H. (2012). Intranasal leptin reduces appetite and induces weight loss in rats with diet-induced obesity (DIO). Endocrinology, 153(1), 143-153.

Adapted from Study Designs; in NICHSR Introduction to Health Services Research: a Self-Study Course

Test-Tube Lab Research

"Test tube" experiments conducted in a controlled laboratory setting.

Adapted from Study Designs; in NICHSR Introduction to Health Services Research: a Self-Study Course