A graphical method for determination of dissociation constants of enzyme inhibitors. Where I is total inhibitor concentration and α is the ratio of inhibited to non-inhibited rates, a plot of Iα/(1-α) on the ordinate (y-axis) against substrate concentration on the abscissa (x-axis) will give a line that intersects the ordinate at K_i; if inhibition is competitive, the slope of the plot is K_i/K_m, if non-competitive, the slope is zero. The advantage of this method lies in its not requiring that data be collected at constant substrate or inhibitor concentration.