Monday, July 16 2012, 10am Room 307, Statistics Building Xue PhD Candidate, Statistics In this dissertation, I propose an empirical likelihood based method to solve the nonresponse problem and changepoint detection problem. Both methods avoid potential model misspecification problems from which existing parametric methods may suffer. Moreover, the proposed imputation method can correct the bias of the estimate of the complete data for distributions with under- or over-dispersion problem. And the empirical likelihood changepoint detection method is able to detect the change in parameters other than the population mean.