Maximin Efficiencies under Treatment-Dependent Costs and Outcome Variances for Parallel, AA/BB, and AB/BA Designs

Table 1

Optimal allocation ratios and corresponding variances of the ML estimator of the treatment effect and the treatment by period interaction for different designs under heterogeneity of outcome variances and costs.

Treatment effect
Design	Allocation ratio (n1/n2)
Crossover design	1
Parallel design
Extended parallel design
Treatment by period interaction
Design	Allocation ratio (n1/n2)
Crossover design	1
Extended parallel design

Note. n₁: sample size for A (parallel design), AB (crossover design), or AA (extended parallel design) sequence; n₂: sample size for B (parallel design), BA (crossover design), or BB (extended parallel design) sequence;