قارن الطرق

	تجربة عشوائية عنقودية متعددة الأذرع	تجربة عشوائية متصالبة محكومة
المجال	التصميم التجريبي	التصميم التجريبي
العائلة	Process / pipeline	Process / pipeline
سنة النشأة	1990s–2000s (systematic formalization)	1960s (Grizzle 1965 for statistical foundations); widely used in clinical research since the 1970s
صاحب الطريقة	Building on cluster randomization (Donner & Klar) and multi-arm trial methods developed in clinical and public health research	Early formalized by statisticians including Bradford Hill and colleagues in clinical trials; theoretical framework developed by Grizzle (1965) and later Senn (2002)
النوع	Experimental design	Experimental within-subject design
المصدر التأسيسي	Donner, A., & Klar, N. (2000). Design and Analysis of Cluster Randomization Trials in Health Research. Arnold. ISBN: 978-0340691533	Senn, S. (2002). Cross-over Trials in Clinical Research (2nd ed.). Wiley. ISBN: 978-0471496533
الأسماء البديلة	multi-arm cluster RCT, cluster-randomized multi-group trial, multi-arm group-randomized trial, CRCT multi-arm	crossover RCT, crossover trial, within-subject RCT, AB/BA crossover design
ذات صلة	6	5
الملخص	A cluster randomized multi-arm experiment assigns intact groups — such as schools, clinics, or villages — rather than individuals to three or more experimental conditions simultaneously. Randomization occurs at the cluster level to prevent contamination between arms, while the multi-arm structure allows simultaneous evaluation of several interventions against a common control or each other, improving efficiency over a series of two-arm studies.	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.