In contrast to the classical discrete choice experiment, the respondent in a rank-order discrete choice experiment, is asked to rank a number of alternatives instead of the preferred one. In this paper, we study the information matrix of a rank order nested multinomial logit model (RO.NMNL) and introduce local D-optimality criterion, then we obtain Locally D-optimal design for RO.NMNL models in...

We investigate the complexity of counting the number of integer points in tropical polytopes, and the complexity of calculating their volume. We study the tropical analogue of the outer parallel body and establish bounds for its volume. We deduce that there is no approximation algorithm of factor α = 2 for the volume of a tropical polytope given by n vertices in a space of dimension m, unless P...

Matrix approximation is a common tool in recommendation systems, text mining, and computer vision. A prevalent assumption in constructing matrix approximations is that the partially observed matrix is of low-rank. We propose a new matrix approximation model where we assume instead that the matrix is locally of low-rank, leading to a representation of the observed matrix as a weighted sum of low...

BACKGROUND Laparoscopic surgery for middle and lower rectal cancer remain controversial because anatomical and complex surgical procedures specifically influence oncologic outcomes. This study analyzes the long-term outcomes of laparoscopic versus open surgery for middle and lower rectal cancer. METHODS Patients (laparoscopic: n = 129, open: n = 152) who underwent curative resection for middl...