手法を比較

	Blocked Randomized Controlled Trial	クラスターランダム化比較試験
分野	実験計画法	実験計画法
系統	Process / pipeline	Process / pipeline
提唱年	1920s (Fisher's blocking principle); applied to RCTs from the 1940s onward	1978–1980s
提唱者	R. A. Fisher (blocking principle); systematic RCT application by Bradford Hill and later Pocock, Friedman et al.	Cornfield (1978); systematised by Donner and colleagues (1980s)
種類	Experimental design	Experimental design
原典	Friedman, L. M., Furberg, C. D., DeMets, D. L., Reboussin, D. M., & Granger, C. B. (2010). Fundamentals of Clinical Trials (4th ed.). Springer. ISBN: 978-1441915856	Donner, A., & Klar, N. (2000). Design and Analysis of Cluster Randomization Trials in Health Research. Arnold. ISBN: 978-0340652978
別名	blocked RCT, block-randomized trial, stratified block randomization trial, permuted block randomization	cluster RCT, group-randomized trial, community randomized trial, cluster-randomized experiment
関連	5	4
概要	A blocked randomized controlled trial (blocked RCT) uses permuted-block randomization to ensure that treatment groups remain balanced in size — and optionally in key characteristics — throughout recruitment. Within each block of fixed or randomly varied size, all treatment allocations are present in equal numbers, so imbalance cannot accumulate even if the trial is stopped early. This makes blocked RCTs the standard randomization approach in clinical and behavioral intervention research.	A cluster randomized controlled trial (cluster RCT) is an experimental design in which intact social or organisational groups — such as schools, clinics, villages, or workplaces — are randomly assigned to treatment conditions rather than individual participants. Outcomes are still measured at the individual level, but the unit of randomization is the cluster. This design is essential when an intervention is delivered to whole groups, when there is a risk of contamination between participants in the same setting, or when individual randomization is logistically or ethically impractical.