Confidence Intervals in Trials of Various Sample Size
Abbreviation: RRR, relative risk reduction.
Two studies with the same point estimate, a 25% RRR, but different sample sizes and correspondingly different CIs. The x-axis represents the different
possible RRR, and the y-axis represents the likelihood of the true RRR having that particular value. The solid line represents the CI around the first
example, in which there were 100 patients per group, and the number of events in the active and control groups were 15 and 20, respectively. The dashed
line represents the CI around the second example, in which there were 1000 patients per group, and the number of events in the active and control groups
Source: Therapy (Randomized Trials), Users' Guides to the Medical Literature: A Manual for Evidence-Based Clinical Practice,
were 150 and 200, respectively.
3rd ed
Citation: Guyatt G, Rennie D, Meade MO, Cook DJ. Users' Guides to the Medical Literature: A Manual for Evidence-Based
Clinical Practice, 3rd ed; 2015 Available at: http://mhmedical.com/ Accessed: July 28, 2017
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