Figure 1

Exemplary description of non-wear time (NWT) validation using consecutive time periods for calculation of sensitivity and specificity of NWT algorithms to detect NWT periods >60 to >180 minutes (black rectangles, wear time based on 24 h-accelerometry or diary data, respectively; white rectangles, NWT based on 24 h-accelerometry or diary data, respectively). As an example, in the original diary data (panel I), five NWT periods during waking were reported being 30, 30, 115, 130, and 30 minutes, respectively. When applying the 60-min NWT algorithm (panel II), two of all NWT periods in diary (115 and 130 minutes, respectively); at the same time, three NWT periods occurred based on the 24 h-accelerometry data (accelero.) during waking (65 and 140 minutes, respectively) and sleeping (75 minutes). Using the 90-min NWT algorithm (panel III), two NWT periods in diary were still detected (115 and 130 minutes, respectively); based on accelerometry, one NWT period was detected (140 minutes). No NWT was detected in diary or accelerometry data when applying the 150-min algorithm (panel IV). For each NWT algorithm, detected NWT periods were classified according to the fourfold table in panel V. Sensitivity (proportion of true positively identified NWT) and specificity (proportion of true negatively identified NWT) were then calculated using the formulas in panel VI.