Detailed theory on a method of analysis of kinetic data based on sample size autocorrelation function was developed to identify the presence of reaction path heterogeneity based on the master equation approach. The behavior of such functions under ideal conditions as well as under heterogeneity conditions was discussed and some of the potential applications of this method have been summarized. Application of this theory to renaturation kinetics of DNA not only revealed the presence of path heterogeneity in the second zipping phase and quantified it but also proved that it was due to nonreactive modes of dynamics on conformational energy landscape, which agreed well with earlier studies.