手法を比較

	要因ランダム化比較試験（Factorial Randomized Controlled Trial）	クロスオーバーランダム化比較試験（Crossover 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 (Fisher factorial foundations); 2000s–2010s (clinical factorial RCT formalization)	1960s (Grizzle 1965 for statistical foundations); widely used in clinical research since the 1970s
提唱者	R. A. Fisher (factorial design foundations); adapted into clinical trials via MOST framework (Collins et al., 2014)	Early formalized by statisticians including Bradford Hill and colleagues in clinical trials; theoretical framework developed by Grizzle (1965) and later Senn (2002)
種類	Experimental trial design	Experimental within-subject design
原典	Collins, L. M., Dziak, J. J., Kugler, K. C., & Trail, J. B. (2014). Factorial experiments: Efficient tools for evaluation of intervention components. American Journal of Preventive Medicine, 47(4), 498–504.	Senn, S. (2002). Cross-over Trials in Clinical Research (2nd ed.). Wiley. ISBN: 978-0471496533
別名	Factorial RCT, factorial trial, multi-factor RCT, factorial experiment with randomization	crossover RCT, crossover trial, within-subject RCT, AB/BA crossover design
関連	6	5
概要	A factorial randomized controlled trial (factorial RCT) is an experimental design in which participants are randomly assigned to every possible combination of two or more independent factors (treatments or intervention components) simultaneously. This allows researchers to estimate the main effect of each factor and their interactions within a single, efficient trial, rather than running separate experiments for each factor.	A crossover randomized controlled trial (crossover RCT) is an experimental design in which each participant receives all study interventions in a randomized sequence, separated by a washout period. Because every participant serves as their own control, within-subject variability is eliminated from the treatment comparison, yielding greater statistical power per participant than a parallel-group RCT of equal size.