Fig. 1
From: Robot-assisted and conventional therapies produce distinct rehabilitative trends in stroke survivors
Rehabilitative trends obtained from principal components analysis (PCA). Consider the schematic case of three outcomes, where the change in each outcome with therapy is plotted for all subjects. PCA finds the best linear fit to the data using 3 perpendicular vectors: the 1st, 2nd, and 3rd principal components (PCs), labeled in descending order by variance explained. Each PC is a rehabilitative trend that quantifies the correlations among outcomes