Table 2.

Precision of sensitivity and specificity estimation (delirium versus control comparison)

Sample size	Parameter	True level of parameter	95% CI width
500	Sensitivity	0.5	±0.098
	Sensitivity	0.7	±0090
	Sensitivity	0.9	±0.059
	Specificity	0.5	±0.049
	Specificity	0.7	±0.045
	Specificity	0.9	±0.029

The sensitivity precision in the delirium versus dementia comparison will be identical to the details outlined above, as the size of the delirium target group is unchanged. The dementia group is similar in size to the delirium group, hence the precision of specificity estimation in this comparison will be similar to that given for sensitivity. These estimates are based on a delirium prevalence of 20%