Date of Award

2017-01-01

Degree Name

Master of Science

Department

Mathematical Sciences

Advisor(s)

Xiaogang Su

Abstract

The maximally selected statistic approach in building tree models is shown to be a cause of variable selection bias. In this study we propose three methods to solve this problem in building regression trees with nominal predictor variables. Out of the three methods

proposed we explored only two in detail and defer one for further research. We developed an exact method to compute the p-value corresponding to the maximized splitting statistic in regression trees for nominal predictor variables with at most 10 distinct levels and a

method to estimate the best cutoff point as a parameter in a parametric nonlinear mixed-effect model in regression trees for nominal predictor variables with any number of distinct levels. The methods are shown to overcome the variable selection bias in an extensive

simulation study and in a real data example.

Language

en

Provenance

Received from ProQuest

File Size

63 pages

File Format

application/pdf

Rights Holder

Isaac Xoese Ocloo

Share

COinS