Table 2. Epoch-by-Epoch Sleep/Wake Agreement between Armband, Actiwatch and PSG.

Measure	Armband n = 50	Actiwatch n = 33
	Mean (95% CI)	Mean (95% CI)
Sensitivity	0.90 (0.88 to 0.93)	0.90 (0.88 to 0.93)
Specificity	0.54 (0.46 to 0.62)	0.67 (0.60 to 0.74)
Agreement	0.85 (0.81 to 0.88)	0.88 (0.86 to 0.90)
PABAK	0.69 (0.63 to 0.75)	0.77 (0.73 to 0.81)

Sensitivity is the proportion of “sleep” epochs as defined by PSG that were judged as “sleep” by Armband/Actiwatch. Specificity is the proportion of the “wake” epochs as defined by PSG that were judged as “wake” by Armband/Actiwatch. Agreement is proportion of epochs where there was agreement between PSG and instrument. PABAK is the prevalence and bias adjusted kappa.