Pulse variability analysis products from the LOFAR observation on 2013 April 7, for the Q mode (left) and the B mode (right). Upper panels: the normalized integrated pulse profile (solid line), the longitude-resolved standard deviation (open circles), and the longitude-resolved modulation index (dimensionless quantity shown as the solid line with error bars). Lower panels: the LRFS is shown, with its horizontal integration to the left.