Table 1.

Isomorphism and causal effects on statistical power.

Empirical component	Choice	Effect on statistical power
Measurement of outcome	Categorical outcome	Decreased statistical power
	Ordinal outcome	Decreased statistical power
	Continuous outcome	Increased statistical power
Research design	Between-subjects	Decreased statistical power
	Within-subjects	Increased statistical power
	Multivariate	Decreased statistical power
Magnitude of effect size	Small effect size	Decreased statistical power
	Large effect size	Increased statistical power
Variance of effect size	Homogeneity	Increased statistical power
	Heterogeneity	Decreased statistical power
Sample size	Small sample size	Decreased statistical power
	Large sample size	Increased statistical power