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Activity Number:
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474
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Type:
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Contributed
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Date/Time:
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Wednesday, August 5, 2009 : 10:30 AM to 12:20 PM
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Sponsor:
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Biometrics Section
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| Abstract - #303548 |
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Title:
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Estimation of Parameters Subject to Order Restrictions on a Circle with Application to Estimation of Phase Angles of Cell Cycle Genes
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Author(s):
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Cristina Rueda and Miguel A. Fernández and Shyamal D. Peddada*+
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Companies:
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Universidad de Valladolid and Universidad de Valladolid and National Institute of Environmental Health Sciences
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Address:
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Biostatistics Branch, Alexander Dr., Raleigh, NC, 27709,
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Keywords:
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Circular isotonic regression ; Order restrictions on circle ; Pool-Adjacent-Violator-Algorithm (PAVA) ; Phase angles ; Restricted maximum likelihood estimators ; Von Mises distribution
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Abstract:
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Motivated by a problem encountered in the analysis of cell cycle gene expression data, this work deals with the estimation of parameters subject to order restrictions on a unit circle. A normal eukaryotic cell cycle has four major phases during cell-division and a cell cycle gene has its peak expression (phase angle) during the phase that may correspond to its biological function. Since the phases are ordered along a circle, the phase angles of cell cycle genes are ordered unknown parameters on a unit circle. The problem of interest is to estimate the phase angles using the information regarding the order among them. Due to the underlying geometry, the standard algorithm can not be used so we develop a circular version of the well known isotonic regression for Euclidean data. We illustrate the new ordered estimator by estimating the phase angles of some well known cell cycle genes.
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