Table 3. Intraclass correlations between Fitbit and Actigraph and between devices and direct observations.
ICC Actigraph vs direct observation | ICC Fitbit vs direct observation | ICC Fitbit vs Actigraph | |||||||
---|---|---|---|---|---|---|---|---|---|
Average ICC | (95% CI) | P | Average ICC | (95% CI) | p | Average ICC | (95% CI) | p | |
Walking step count | |||||||||
First measures | 0.67 | (-0.23, 0.90) | <0.001 | 0.11 | (-0.48, 0.55) | 0.353 | 0.09 | (-0.23, 0.43) | 0.298 |
Second measures | 0.75 | (0.29, 0.91) | 0.001 | 0.00 | (-0.29, 0.37) | 0.503 | 0.16 | (-0.17, 0.50) | 0.097 |
Average of measures | 0.73 | (-0.14, 0.91) | <0.001 | 0.05 | (-0.30, 0.42) | 0.390 | 0.10 | (-0.15, 0.39) | 0.195 |
Incline walking step count | |||||||||
First measures | 0.75 | (-0.17, 0.93) | <0.001 | 0.07 | (-0.82, 0.57) | 0.421 | -0.06 | (-0.66, 0.42) | 0.583 |
Second measures | 0.71 | (0.31, 0.88) | 0.002 | 0.19 | (-0.58, 0.63) | 0.281 | 0.21 | (-0.33, 0.60) | 0.202 |
Average of measures | 0.74 | (0.07, 0.91) | <0.001 | 0.11 | (-0.58, 0.56) | 0.356 | 0.02 | (-0.45, 0.43) | 0.467 |
Jogging step count | |||||||||
First measures | 0.57 | (-0.20, 0.84) | 0.001 | 0.40 | (-0.39, 0.74) | 0.116 | 0.58 | (0.08, 0.81) | 0.008 |
Second measures | 0.35 | (-0.25, 0.71) | 0.035 | 0.11 | (-1.22, 0.65) | 0.399 | 0.38 | (-0.34, 0.73) | 0.116 |
Average of measures | 0.46 | (-0.23, 0.78) | 0.005 | 0.34 | (-0.41, 0.71) | 0.145 | 0.52 | (-0.01, 0.78) | 0.018 |
Stair stepping | |||||||||
First measures | 0.18 | (-1.01, 0.66) | 0.329 | -0.06 | (-1.63, 0.56) | 0.553 | 0.69 | (0.28, 0.86) | 0.004 |
Second measures | 0.53 | (-0.10, 0.81) | 0.041 | 0.51 | (-0.32, 0.81) | 0.077 | 0.43 | (-0.26, 0.75) | 0.085 |
Average of measures | 0.42 | (-0.36, 0.75) | 0.104 | 0.01 | (-1.48, 0.59) | 0.491 | 0.72 | (0.38, 0.88) | 0.001 |
CI: confidence interval, ICC: Intraclass correlation