Analysis of the effects on am of (left column) power input to the magnetosphere P_α/P_o at a given solar wind dynamic pressure p_SW and of (right column) the effects of p_SW at a given P_α/P_o. Values of am/<am>_all are plotted as a function of corresponding normalised values of (left) P_α and (right) p_SW. In (a) data are averaged into 5 quantile ranges of the normalised solar wind dynamic pressure p_SW/<p_SW>_all, 36 bins of time-of-year F, and by the polarity of the IMF Y component in GSEQ, [B_Y]_GSEQ: the means of am/<am>_all are plotted against the corresponding means of P_α/P_o. In (b) data are averaged into 5 quantiles of normalised power input to the magnetosphere P_α/P_o, 36 bins of time-of-year F, and by the [B_Y]_GSEQ polarity and the means of am/<am>_all are plotted against the corresponding means of p_SW/<p_SW>_all. The black lines in the upper panels are 3rd-order polynomial fits in each case, fitted to data for all [B_Y]_GSEQ drawn over the range of the averaged data for the quantile range in question. The points are coloured according to the quantile range as given by the key. The lines are also plotted (this time using the same colours as the points in the upper panels) in the corresponding lower panel. The grey points show a scatter plot of all 10-day average values.