The purpose of this study was to compare steps•d -1 between an accelerometer and pedometer in 2 free-living samples. Methods: Data from 2 separate studies were used for this secondary analysis (Sample 1: N = 99, Male: n = 28, 20.9 ± 1.4 yrs, BMI = 27.2 ± 5.0 kg•m -2 , Female: n = 71, 20.9 ± 1.7 yrs, BMI = 22.7 ± 3.0 kg•m -2 ; Sample 2: N = 74, Male: n = 27, 38.0 ± 9.5 yrs, BMI = 25.7 ± 4.5 kg•m -2 , Female: n = 47, 38.7 ± 10.1 yrs, BMI = 24.6 ± 4.0 kg•m -2 ). Both studies used identical

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... es and analytical strategies. Results: The mean difference in steps•d -1 for the week was 1643.4 steps•d -1 in Study 1 and 2199.4 steps•d -1 in Study 2. There were strong correlations between accelerometer-and pedometer-determined steps•d -1 in Study 1 (r = .85, P < .01) and Study 2 (r = 0.87, P < .01). Bland-Altman plots indicated agreement without bias between steps recorded from the devices in Study 1 (r = -0.14, P < .17) and Study 2 (r = -0.09, P < .40). Correlations examining the difference between accelerometer-pedometer steps•d -1 and MVPA resulted in small, inverse correlations (range: r = -0.03 to -0.28). Conclusions: These results indicate agreement between accelerometerand pedometer-determined steps•d -1 ; however, measurement bias may still exist because of known sensitivity thresholds between devices.