Table 2.

Sample size assessment for excretion of mannitol and lactulose: effect sizes detectable with ∼80% power for two groups based on HLA-DQ genotype

Response	Difference Detectable (80% Power)		Effect Size
	n = 12	n = 24*	n = 12	n = 24*
Mannitol excretion
0–2 h	21 mg/h	14 mg/h	44%	29%
Cumulative 2–24 h	84 mg	58 mg	40%	28%
Lactulose excretion
Cumulative 2–24 h	27 mg	19 mg	60%	42%

Difference detectable is based on a 2-sample t-test (2-sided α = 0.05). Effect size is difference as percentage of overall mean.

^*Detectable for overall main effect of diet.