Unlike simple-randomized trials, where you need to consider only the number of subjects, in cluster-randomized and multi-site trials you need to consider the number of units at each level of the study design. If you ignore these, you might compute power as 90% when the actual value is 50% or even lower.
Your real challenge, however, is not only to compute the correct power, but to design the most cost-effective study.
In simple randomized trials, the only sample size you can manipulate is the number of subjects. By contrast, in a cluster-randomized or multi-site trial you can manipulate (for example) the number of school districts, schools, classes, and students. Or, the number of hospitals, doctors and patients.
Typically, there are many combinations of these numbers that will yield the same power but (in common scenarios) some may cost twice as much as others. In this course you will learn how to quickly and confidently find the best options, taking into account both cost and practical considerations.
In this course Dr. Borenstein will explain how cluster-randomization and/or the use of multiple sites affect power. Then, he will show how to take account of these issues when planning a study.
The course will cover the following topics
How the course works
About the software
Dr. Borenstein is the co-author (with Larry Hedges) of CRT-Power, a program developed with funding from the National Institutes of Health (see below for details).
More info about the online course:
More info about the software:
About the instructor:
Dr. Borenstein has taught numerous workshops and online courses on power analysis and meta-analysis, and is widely recognized for his ability to communicate difficult concepts in ways that are accessible to researchers as well as statisticians.
For Indian participants statistics.com accepts registration for its courses at special prices in Indian Rupees through its partner, the Center for eLearning and Training (C-eLT), Pune.