SSRN Author: J. Douglas CarrollJ. Douglas Carroll SSRN Content
http://www.ssrn.com/author=2200619
http://www.ssrn.com/rss/en-usFri, 14 Jul 2017 02:12:09 GMTeditor@ssrn.com (Editor)Fri, 14 Jul 2017 02:12:09 GMTwebmaster@ssrn.com (WebMaster)SSRN RSS Generator 1.0New: Tree Representations of Rectangular Proximity MatricesA least-squares algorithm for fitting ultrametric and path length or additive trees to two-way, two-mode proximity data is presented. The algorithm utilizes a penalty function to enforce the ultrametric inequality generalized for asymmetric, and generally rectangular (rather than square) proximity matrices in estimating an ultrametric tree. This stage is used in an alternating least-squares fashion with closed-form formulas for estimating path length constants for deriving path length trees.
http://www.ssrn.com/abstract=2783474
http://www.ssrn.com/1607329.htmlThu, 13 Jul 2017 06:41:11 GMTNew: Least Squares Algorithms for Constructing Constrained Ultrametric and Additive Tree Representations of Symmetric Proximity DataA mathematical programming algorithm is developed for fitting ultrametric or additive trees to proximity data where external constraints are imposed on the topology of the tree. The two procedures minimize a least squares loss function. The method is illustrated on both synthetic and real data. A constrained ultrametric tree analysis was performed on similarities between 32 subjects based on preferences for ten odors, while a constrained additive tree analysis was carried out on some proximity data between kinship terms. Finally, some extensions of the methodology to other tree fitting procedures are mentioned.
http://www.ssrn.com/abstract=2784845
http://www.ssrn.com/1606596.htmlMon, 10 Jul 2017 15:18:16 GMT