Table 4. Correlation and agreement between time in physical activity and moderate to vigorous physical activity derived from Fitbit and Actigraph.

	Epoch level, Scripted tasks	Epoch level, Free living	Daily level, Free living		Average level, Free living
Comparison	k [95% CI]	k [95% CI]	r [95% CI]	CCC [95% CI]	r [95% CI]	CCC [95% CI]
Physical Activity
Act(VM) vs Act(Vert) a	0.93 [0.88–0.97]	0.75 [0.73–0.77]	0.78 [0.74–0.83]	0.34 [0.25–0.41]	0.92 [0.85–0.96]	0.71 [0.57–0.81]
Fitbit vs Act(Vert)	0.87 [0.72–1.02]	0.76 [0.73–0.80]	0.74 [0.67–0.80]	0.36 [0.21–0.50]	0.72 [0.50–0.85]	0.52 [0.32–0.68]
Fitbit vs Act(VM)	0.85 [0.71–0.99]	0.62 [0.58–0.66]	0.82 [0.77–0.86]	0.18 [0.11–0.26]	0.76 [0.57–0.87]	0.35 [0.20–0.49]
Moderate to Vigorous Physical Activity
Act(Uni) vs Act(Sev) a	0.84 [0.77–0.91]	0.82 [0.75–0.89]	0.79 [0.68–0.86]	0.63 [0.46–0.74]	0.89 [0.79–0.94]	0.87 [0.77–0.93]
Act(Uni) vs Act(Sasaki) a	0.79 [0.63–0.94]	0.73 [0.66–0.80]	0.82 [0.72–0.88]	0.63 [0.47–0.73]	0.90 [0.82–0.95]	0.88 [0.78–0.94]
Act(Sev) vs Act(Sasaki) a	0.76 [0.63–0.88]	0.68 [0.60–0.76]	0.78 [0.65–0.85]	0.56 [0.38–0.66]	0.76 [0.57–0.87]	0.72 [0.53–0.84]
Fitbit vs Act(Uni)	-0.18 [-0.48–0.13]	0.39 [0.27–0.51]	0.68 [0.56–0.80]	0.45 [0.27–0.63]	0.80 [0.64–0.90]	0.80 [0.64–0.89]
Fitbit vs Act(Sev)	-0.18 [-0.48–0.13]	0.42 [0.31–0.54]	0.65 [0.55–0.75]	0.41 [0.27–0.56]	0.64 [0.40–0.81]	0.63 [0.39–0.79]
Fitbit vs Act(Sasaki)	-0.18 [-0.46–0.10]	0.41 [0.31–0.52]	0.67 [0.54–0.79]	0.44 [0.27–0.58]	0.79 [0.62–0.89]	0.78 [0.61–0.88]

^a Comparison between two criterion measures

Point estimates which did not reach statistical significance, defined here as the 95% confidence intervals excluding 0, are shown in italics.

Act: Actigraph; Vert: Vertical; VM: Vector Magnitude; Uni: Uniform; Sev: Severity; k: Fleiss’ kappa; CI: confidence interval; r: Pearson correlation coefficient; CCC: Lin’s Concordance correlation coefficient