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