7-days of valid data). Using only dates from the log and the Choi algorithm yielded: 1) larger samples with valid data than using log dates and times, 2) similar wear-times as using log dates and times, 3) more wear-time (V, 48.1 min more; VM, 29.5 min more) than only log dates and Troiano algorithm. Wear-time algorithm impacted sedentary time (~30-60 min lower for Troiano vs. Choi) but not moderate-to-vigorous (MV) PA time. Using V-axis cut-points yielded ~60 min more sedentary time and ~10 min less MVPA time than using VM cut-points. Conclusions Combining log-dates and the Choi algorithm was optimal, minimizing missing data and researcher burden. Estimates of time in physical activity and sedentary behavior are not directly comparable between V-axis and VM cut-points. These findings will inform consensus development for accelerometer data processing in ongoing epidemiologic studies."/>
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Figure 2 | BMC Public Health

Figure 2

From: Impact of accelerometer data processing decisions on the sample size, wear time and physical activity level of a large cohort study

Figure 2

Bland-Altman plot of MVPA (min/d) for vertical axis and vector magnitude. Note: Solid line is mean bias and dashed lines are 95% limits of agreement. MVPA is defined as time during which the accelerometer registers vertical cpm > = 1952 [12] and VM cpm > = 2691 [22]. Monitor-wear time was estimated using Limited-log + Choi [10, 19].

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