Morris, J.S. and Vannucci, M. and Brown, P.J. and Carroll, R.J. (2003) Wavelet-based nonparametric modeling of hierarchical functions in colon carcinogenesis. Journal of the American Statistical Association, 98 (463). pp. 573-583. ISSN 0162-1459.
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In this article we develop new methods for analyzing the data from an experiment using rodent models to investigate the effect of type of dietary fat on O-6-methylguanine-DNA-methyltransferase (MGMT), an important biomarker in early colon carcinogenesis. The data consist of observed profiles over a spatial variable contained within a two-stage hierarchy, a structure that we dub hierarchical functional data. We present a new method providing a unified framework for modeling these data, simultaneously yielding estimates and posterior samples for mean, individual, and subsample-level profiles, as well as covariance parameters at the various hierarchical levels. Our method is nonparametric in that it does not require the prespecification of parametric forms for the functions and involves modeling in the wavelet space, which is especially effective for spatially heterogeneous functions as encountered in the MGMT data. Our approach is Bayesian; the only informative hyperparameters in our model are effectively smoothing parameters. Analysis of this dataset yields interesting new insights into how MGMT operates in early colon carcinogenesis, and how this may depend on diet. Our method is general, so it can be applied to other settings where hierarchical functional data are encountered.
|Uncontrolled keywords:||Bayesian method; carcinogenesis; functional data analysis; hierarchical model; model averaging; nonparametric regression; wavelet|
|Subjects:||H Social Sciences > HA Statistics|
|Divisions:||Faculties > Science Technology and Medical Studies > School of Mathematics Statistics and Actuarial Science|
|Depositing User:||Judith Broom|
|Date Deposited:||19 Dec 2007 18:20|
|Last Modified:||14 Jan 2010 13:58|
|Resource URI:||http://kar.kent.ac.uk/id/eprint/556 (The current URI for this page, for reference purposes)|
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