Method and apparatus for displaying alternans data of an electrocardiogram signal having a plurality of odd beats and a plurality of even beats. The method can include calculating an odd median complex for at least one of the plurality of odd beats, the odd median complex having a plurality of odd data points; calculating an even median complex for at least one of the plurality of even beats, the even median complex having a plurality of even data points; comparing the plurality of odd data points with the plurality of even data points to generate a plurality of difference data points; assigning each one of the plurality of difference data points a color corresponding to an amplitude; displaying the plurality of difference data points as a difference curve; and displaying a plurality of difference curves in a temporal alignment.