A model where the least trimmed squares estimator is maximum likelihood

<p>The least trimmed squares (LTS) estimator is a popular robust regression estimator. It finds a subsample of&nbsp;<em>h</em>&nbsp;&lsquo;good&rsquo; observations among&nbsp;<em>n</em>&nbsp;observations and applies least squares on that subsampl...

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Bibliographic Details
Main Authors: Berenguer-Rico, V, Johansen, S, Nielsen, B
Format: Journal article
Language:English
Published: Wiley 2023
Description
Summary:<p>The least trimmed squares (LTS) estimator is a popular robust regression estimator. It finds a subsample of&nbsp;<em>h</em>&nbsp;&lsquo;good&rsquo; observations among&nbsp;<em>n</em>&nbsp;observations and applies least squares on that subsample. We formulate a model in which this estimator is maximum likelihood. The model has &lsquo;outliers&rsquo; of a new type, where the outlying observations are drawn from a distribution with values outside the realized range of&nbsp;<em>h</em>&nbsp;&lsquo;good&rsquo;, normal observations. The LTS estimator is found to be <em>h</em><sup>1/2</sup> consistent and asymptotically standard normal in the location-scale case. Consistent estimation of&nbsp;<em>h</em>&nbsp;is discussed. The model differs from the commonly used&nbsp;<em>ϵ</em>-contamination models and opens the door for statistical discussion on contamination schemes, new methodological developments on tests for contamination as well as inferences based on the estimated good data.</p>