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<title>Kyungduk Ko</title>
<copyright>Copyright (c) 2011  All rights reserved.</copyright>
<link>http://works.bepress.com/kyungduk_ko</link>
<description>Recent documents in Kyungduk Ko</description>
<language>en-us</language>
<lastBuildDate>Thu, 23 Jun 2011 05:27:35 PDT</lastBuildDate>
<ttl>3600</ttl>


	
		
	







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<title>Inducing Normality from Non-Gaussian Long Memory Time Series and Its Application to Stock Return Data</title>
<link>http://works.bepress.com/kyungduk_ko/6</link>
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<pubDate>Tue, 21 Jun 2011 15:48:02 PDT</pubDate>
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	<p>Motivated by Lee and Ko (<em>Appl. Stochastic Models. Bus. Ind.</em> 2007; <strong>23</strong>:493–502)  but not limited to the study, this paper proposes a wavelet-based  Bayesian power transformation procedure through the well-known Box–Cox  transformation to induce normality from non-Gaussian long memory  processes. We consider power transformations of non-Gaussian long memory  time series under the assumption of an <em>unknown</em> transformation  parameter, a situation that arises commonly in practice, while most  research has been devoted to non-linear transformations of Gaussian long  memory time series with <em>known</em> transformation parameter.  Specially, this study is mainly focused on the simultaneous estimation  of the transformation parameter and long memory parameter. To this end,  posterior estimations via Markov chain Monte Carlo methods are performed  in the wavelet domain. Performances are assessed on a simulation study  and a German stock return data set.</p>

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<author>Kyungduk Ko</author>


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<title>Wavelet-based Bayesian Estimation of Partially Linear Regression Models with Long Memory Errors</title>
<link>http://works.bepress.com/kyungduk_ko/5</link>
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<pubDate>Fri, 10 Sep 2010 09:58:09 PDT</pubDate>
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	<p>In this paper we focus on partially linear regression models with long memory errors, and propose a wavelet-based Bayesian procedure that allows the simultaneous estimation of the model parameters and the nonparametric part of the model. Employing discrete wavelet transforms is crucial in order to simplify the dense variance-covariance matrix of the long memory error. We achieve a fully Bayesian inference by adopting a Metropolis algorithm within a Gibbs sampler. We evaluate the performances of the proposed method on simulated data. In addition, we present an application to Northern hemisphere temperature data, a benchmark in the long memory literature.</p>

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<author>Kyungduk Ko et al.</author>


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<title>Confidence Intervals for Long Memory Regressions</title>
<link>http://works.bepress.com/kyungduk_ko/4</link>
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<pubDate>Tue, 29 Sep 2009 09:59:49 PDT</pubDate>
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	<p>This paper proposes an accurate condence interval for the trend parameter in a linear regression model with long memory errors. The interval is based upon an equivalent sum of squares method and is shown to perform comparably to a weighted least squares interval. The advantages of the proposed interval lies in its relative ease of computation and should be attractive to practitioners.</p>

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<author>Kyungduk Ko et al.</author>


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<title>First-Order Bias Correction for Fractionally Integrated Time Series</title>
<link>http://works.bepress.com/kyungduk_ko/3</link>
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<pubDate>Mon, 21 Sep 2009 11:47:09 PDT</pubDate>
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<author>Jaechoul Lee et al.</author>


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<title>Bayesian Wavelet-Based Methods for the Detection of Multiple Changes of the Long Memory Parameter</title>
<link>http://works.bepress.com/kyungduk_ko/2</link>
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<pubDate>Tue, 21 Jul 2009 15:56:54 PDT</pubDate>
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	<p>Long memory processes are widely used in many scientific fields, such as economics, physics, and engineering. Change point detection problems have received considerable attention in the literature because of their wide range of possible applications. Here we describe a wavelet-based Bayesian procedure for the estimation and location of multiple change points in the long memory parameter of Gaussian autoregressive fractionally integrated moving average models (ARFIMA(p, d, q)), with unknown autoregressive and moving average parameters. Our methodology allows the number of change points to be unknown. The reversible jump Markov chain Monte Carlo algorithm is used for posterior inference. The method also produces estimates of all model parameters. Performances are evaluated on simulated data and on the benchmark Nile river dataset</p>

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<author>Kyungduk Ko</author>


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<title>Wavelet Deconvolution in a Periodic Setting Using Cross-Validation</title>
<link>http://works.bepress.com/kyungduk_ko/1</link>
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<pubDate>Tue, 21 Jul 2009 15:56:54 PDT</pubDate>
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	<p>The wavelet deconvolution method WaveD using band-limited wavelets offers both theoretical and computational advantages over traditional compactly supported wavelets. The translation-invariant WaveD with a fast algorithm improves further. The twofold cross-validation method for choosing the threshold parameter and the finest resolution level in WaveD is introduced. The algorithm’s performance is compared with the fixed constant tuning and the default tuning in WaveD.</p>

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<author>Leming Qu et al.</author>


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