Flexible R functions for processing accelerometer data, with emphasis on NHANES 2003-2006

Abstract

Accelerometers are a valuable tool for measuring physical activity (PA) in epidemiological studies. However, considerable processing is needed to convert time-series accelerometer data into meaningful variables for statistical analysis. This article describes two recently developed R packages for processing accelerometer data. The package accelerometry contains functions for performing various data processing procedures, such as identifying periods of non-wear time and bouts of activity. The functions are flexible, computationally efficient, and compatible with uniaxial or triaxial data. The package nhanesaccel is specifically for processing data from the National Health and Nutrition Examination Survey (NHANES), years 2003-2006. Its primary function generates measures of PA volume, intensity, frequency, and patterns according to user-specified data processing methods. This function can process the NHANES 2003-2006 dataset in under one minute, which is a drastic improvement over existing software. This article highlights important features of packages accelerometry and nhanesaccel and demonstrates typical usage for PA researchers.