Table 4.

Cluster randomized trials

Key features	Group, not individual, is randomized entity
Advantages	Avoids intervention contamination across randomized entities Useful for studying bundled or behavioral interventions
Disadvantages	Larger total sample size (n) Groups may be dissimilar affecting results Power analysis complex Complex results analysis to account for group effect
Example	Prehospital Air Medical Plasma (PAMPer) trial14