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Table 2 Mean (SD), correlations and Bland-Altman output for Fitbit Zip and ActiGraph in school segments

From: Validating Fitbit Zip for monitoring physical activity of children in school: a cross-sectional study

 

Fitbit Zip

ActiGraph GT3x

r

Bias

LoA

LuA

Steps

 Class time

231.5 (298.2)

206.2 (222.9)

0.85**

25.2

− 209.6

260.3

 Physical education lesson

2354.0 (1279.6)

2008.7 (1172.5)**

0.96**

345.3

− 163.8

854.4

 Recess

472.2 (337.2)

388.5 (268.2)**

0.96**

83.7

−127.3

294.7

MVPA (min)

 Class time

0.6 (2.5)

0.9 (1.7)**

0.24**

−0.3

−4.0

3.3

 Physical education lesson

17.8 (14.1)

15.4 (9.1)*

0.72**

2.4

−14.7

19.4

 Recess

2.1 (4.3)

2.4 (2.4)**

0.56**

−0.3

−6.4

5.8

Sedentary time (min)

 Class time

37.5 (5.8)

33.8 (6.5)**

0.57**

3.6

−6.5

13.8

 Physical education lesson

11.1 (9.8)

13.7 (9.0)**

0.85**

−2.6

−10.4

5.2

 Recess

5.5 (4.1)

5.4 (3.9)

0.87**

0.1

−3.7

3.9

  1. Note: * P < 0.05, ** P < 0.001, LoA lower limits of agreement, LuA upper limits of agreement. Differences between two devices according to Wilcoxon Signed Rank test are presented in column “ActiGraph GT3x”