1. A method of determining alternans data of an ECG signal, the method comprising: executing a software program stored in a memory with a processor, such that the executing step effectuates the following steps: determining at least one value representing at least one morphology feature of each beat of the ECG signal, wherein the ECG signal is collected with a data acquisition device; performing a statistical analysis using data points generated based on a total quantity of values and total quantity of beats the statistical analysis generating a confidence level; determining whether the confidence level is significant; processing the data points using a cluster analysis, the cluster analysis generating a first cluster of points and a second cluster of points; separating the data points into a first group of points and a second group of points comparing the first cluster of points with the first group of points; comparing the second cluster of points with the second group of points; and determining a value representative of a first set of matched points between the first cluster of points and the first group of points and a second set of matched points between the second cluster of points and the second group of points; and wherein the confidence level is based at least in part on the value.