The autocalibration method was evaluated based on data collected with wrist-worn raw accelerometry in subsamples of epidemiological cohorts from Africa, Europe, South America, and the Middle-East, representing locations with different gravity. Cohorts included: The Fenland Study (Cambridgeshire, UK) (21 (link)), a repeated cross-sectional survey of the Cameroon Physical Activity Study (3 (link)), the Kuwait Wellbeing Study, and the 1993 Pelotas birth cohort (Brazil) (28 (link)). The data subsamples in each cohort span most local seasons and represent very diverse populations, lifestyles, and environmental conditions. Basic cohort characteristics are described in Table 1 .
The same accelerometer brand was used in all cohorts (GENEActiv; Activinsights, Kimbolton, UK). This accelerometer includes a triaxial acceleration sensor (ADXL345) with a ±8-g dynamic range and a 12-bit resolution and a temperature sensor (MCP9700T). Most of the devices used in the UK and Brazil cohort were older (lower serial number) than the devices used in the Kuwait and Cameroon cohorts. In all cohorts, participants were asked to wear the accelerometer on their nondominant wrist during sleeping and waking hour. All participants provided informed consent, and each study was approved by the local ethics committee.
The same accelerometer brand was used in all cohorts (GENEActiv; Activinsights, Kimbolton, UK). This accelerometer includes a triaxial acceleration sensor (ADXL345) with a ±8-g dynamic range and a 12-bit resolution and a temperature sensor (MCP9700T). Most of the devices used in the UK and Brazil cohort were older (lower serial number) than the devices used in the Kuwait and Cameroon cohorts. In all cohorts, participants were asked to wear the accelerometer on their nondominant wrist during sleeping and waking hour. All participants provided informed consent, and each study was approved by the local ethics committee.
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