Detecting Change-Points in Epidemic Models

The purpose of this research is to propose a new method for detecting change points with an epidemic alternative (in the form of a step function). There are several parametric approaches and nonparametric approaches in the literature that can be used for detecting change-points in epidemic models. Yan [16] summarized some existing parametric approaches. The approaches summarized in Yao's paper are based on the assumption of known population variances. The proposed test statistic in this research does not depend on the assumption of known population variances. This better fits the real world situation. Monte-Carlo simulation was used to find the critical values of the test. The power study was also based on Monte-Carlo simulation. The simulation result shows that the test statistic proposed in this research provides quite decent power compared with other existing statistical procedures, especially for the case that the step is large and duration of the epidemic is long. In 1997, a likelihood ratio test was proposed by Csorgo and Horvath [24]. Compared with the likelihood ratio test, the method proposed in this paper is easier to use by the statistics users.