手法を比較

	ブロック化A/Bテスト	Blocked Randomized Controlled Trial
分野	実験計画法	実験計画法
系統	Process / pipeline	Process / pipeline
提唱年	1926 (blocking principle); 2000s–2010s (online A/B testing application)	1920s (Fisher's blocking principle); applied to RCTs from the 1940s onward
提唱者	R. A. Fisher (blocking principle); adapted to online A/B testing by industry practitioners	R. A. Fisher (blocking principle); systematic RCT application by Bradford Hill and later Pocock, Friedman et al.
種類	Randomized controlled experiment with variance reduction	Experimental design
原典	Fisher, R. A. (1926). The arrangement of field experiments. Journal of the Ministry of Agriculture of Great Britain, 33, 503–513.	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
別名	block-randomized A/B test, stratified A/B test, blocked split test, block-design A/B experiment	blocked RCT, block-randomized trial, stratified block randomization trial, permuted block randomization
関連	4	5
概要	A blocked A/B test is an experimental design that partitions units (users, subjects, or clusters) into homogeneous blocks before randomly assigning them to treatment A or treatment B within each block. Blocking reduces within-experiment noise by ensuring that known sources of variation — such as device type, geography, or user tenure — are balanced across conditions, yielding more precise estimates of the treatment effect than a simple unblocked A/B test.	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.