Accuracy Assessment: Motion Correction

This section details the comparative accuracy of the Motion Correction scheme (MCFLIRT) when tested against two of the most widely-used schemes: SPM and AIR. In order to attempt to establish a ``gold standard'' for registration accuracy, initial tests use the RMS measure (equation 6) in combination with synthetic data, where the exact value of the motion is known, in order to quantify the scheme's ability to correct for subject motion. Later tests characterise the degree of correction by examining the residual variation (collapsed across time) in the corrected data. This measure is also used to test the scheme's effectiveness on real data where we have no absolute measure of the subject's movement.