Table 1.

Advantages and disadvantages of three methods of randomization for future hip protector clinical trials

	Intra-individual randomization	Individual randomization	Cluster randomization
Advantages	Smaller sample size	Less complicated design, implementation, and analysis	Less chance of contamination among the control participants
	Masking to treatment if “sham” protector is convincing	Relatively smaller sample size
	Every participant has the opportunity to receive the intervention
Disadvantages	Each participant should have two intact hips (if sample size is large this problem if obviated)	Substantial risk of contamination/co-intervention	Greater risk of co-interventiona
	Difficult to keep real and sham pads on assigned side	50% of the participants will not benefit from intervention	Care needed with inclusion criteria and falls risk as participants may vary between clusters
	50% of the hips are not protected	Motivation and adherence adversely affected	More complex analysis
	Findings may not be fully generalizable as the device is not utilized in clinical practice		Relatively larger sample size

^aAvoided if cluster randomization to side on which the hip protector is placed (see Kiel et al. 2007)