“…Another typical application of PCA in gait analysis is to investigate and summarize group differences in gait waveform data (e.g., Deluzio et al, 1997;Muniz & Nadal, 2009;Reid et al, 2010;Yamamoto et al, 1983). In these applications, one PCA is often conducted for each joint/muscle/segment using a subjects × time matrix, where the subjects mode is a collection of subjects from different groups (e.g., Astephen et al, 2008;Chester & Wrigley, 2008;Cochran et al, 1984;Donoghue et al, 2008;Lamoth et al, 2006;Lauer et al, 2005;Lee et al, 2009;McKean et al, 2007).…”