Confronta i metodi

	Disegno Solomon a quattro gruppi randomizzato a grappoli	Disegno Solomon a quattro gruppi bloccato
Campo	Disegno sperimentale	Disegno sperimentale
Famiglia	Process / pipeline	Process / pipeline
Anno di origine	1949 (Solomon design); cluster extension formalized in 1990s	1949 (base); blocking extension applied in behavioral and social sciences from mid-20th century onward
Ideatore	Richard L. Solomon (four-group logic, 1949); cluster randomization methods developed by Murray and colleagues in the 1990s	Richard L. Solomon (base design, 1949); blocking integrated from classical experimental design tradition (Fisher, 1935)
Tipo	Experimental design	Experimental design
Fonte seminale	Solomon, R. L. (1949). An extension of control group design. Psychological Bulletin, 46(2), 137–150.	Solomon, R. L. (1949). An extension of control group design. Psychological Bulletin, 46(2), 137–150.
Alias	CR-S4GD, cluster-randomized four-group design, group-randomized Solomon design, Solomon four-group cluster trial	Blocked S4G, randomized blocked Solomon design, Solomon four-group with blocking
Correlati	6	6
Sintesi	The cluster randomized Solomon four-group design combines cluster randomization — assigning intact groups such as schools, clinics, or communities to conditions — with the Solomon four-group structure that isolates the effect of pretesting. Four clusters (or sets of clusters) are created: two receive the treatment and two serve as controls, with only one treatment cluster and one control cluster receiving a pretest, while the others go straight to the posttest. This structure simultaneously controls for pretest sensitization and the logistical constraint that individual randomization is infeasible.	The blocked Solomon four-group design combines Solomon's classic four-group structure — which disentangles pretest sensitization effects from treatment effects — with blocking on a known nuisance variable. Participants are first grouped into homogeneous blocks (e.g., by baseline ability, gender, or site), then randomly assigned within each block to one of four conditions: pretested treatment, pretested control, unpretested treatment, and unpretested control. This structure simultaneously controls for maturation, pretest reactivity, and block-level variance, making it one of the strongest quasi-controlled experimental frameworks available.