Assessment of differenced center of pressure time series improves detection of age-related changes in postural coordination

Center of Pressure (CoP) time series exhibit non-stationarity. Most CoP analyses assume a stationary signal, which could lead to measurement inaccuracy. Despite this, few researchers have reported the incidence of CoP non-stationarity or employed procedures to mitigate non-stationarity prior to time-series analysis. Differencing is a pre-processing technique that reduces non-stationarity, though it has only recently been used with CoP data. This study sought to report the incidence of CoP non-stationarity in a sample data set and determine whether differencing mitigated any CoP non-stationarity that was detected. In addition, researchers examined whether analysis of differenced CoP improved the ability to detect age-related changes in postural coordination. (C) 2012 Elsevier B.V. All rights reserved.