Advances in Decision Sciences
Volume 2011 (2011), Article ID 976823, 16 pages
http://dx.doi.org/10.1155/2011/976823
Research Article

Testing the Correlation and Heterogeneity for Hierarchical Nonlinear Mixed-Effects Models

Qingming Zou1 and Zhongyi Zhu2

1College of Economics and Management, University of South China, Hengyang, Hunan 421001, China
2Department of Statistics, Fudan University, Shanghai 200433, China

Received 6 December 2010; Accepted 31 May 2011

Academic Editor: Wing Keung Wong

Copyright © 2011 Qingming Zou and Zhongyi Zhu. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Nonlinear mixed-effects models are very useful in analyzing repeated-measures data and have received a lot of attention in the field. It is of common interest to test for the correlation within clusters and the heterogeneity across different clusters. In this paper, we address these problems by proposing a class of score tests for the null hypothesis that all components of within- and between-subject variance are zeros in a kind of nonlinear mixed-effects model, and the asymptotic properties of the proposed tests are studied. The finite sample performance of this test is examined through simulation studies, and an illustrative example is presented.