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Embedding R in Windows applications, and executing R remotely

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hoa – A package bundle for higher order likelihood<br />

<strong>in</strong>ference<br />

Aless<strong>and</strong>ra R. Brazzale 1 <strong>and</strong> Ruggero Bellio 2<br />

1 Institute for Biomedical Eng<strong>in</strong>eer<strong>in</strong>g<br />

Italian National Research Council<br />

aless<strong>and</strong>ra.brazzale@isib.cnr.it<br />

2 Department of Statistics<br />

University of Ud<strong>in</strong>e, Italy<br />

ruggero.bellio@dss.uniud.it<br />

S<strong>in</strong>ce its <strong>in</strong>troduction by Sir R. A. Fisher, the likelihood criterion has found extensive<br />

application <strong>in</strong> the analysis of data. The application of the central limit<br />

theorem to conclude that statistics such as the maximum likelihood estimator<br />

are approximately normally distributed, with mean <strong>and</strong> variance consistently estimable<br />

from the data, lead to the theory of first order asymptotic <strong>in</strong>ference.<br />

Over the past twenty-five years or so very accurate approximations, generally<br />

called higher order approximations, to the distribution of the statistics <strong>in</strong>volved<br />

have been developed. Although they are relatively easily derived us<strong>in</strong>g techniques<br />

adapted from the theory of asymptotic expansions, much application of likelihood<br />

<strong>in</strong>ference still relies on first order asymptotics.<br />

The purpose of this presentation is to illustrate how higher order likelihood<br />

theory can be applied <strong>in</strong> practice by us<strong>in</strong>g the software provided through the hoa<br />

package bundle. The <strong>applications</strong> considered are regression models, <strong>in</strong>clud<strong>in</strong>g<br />

logistic regression, non-normal l<strong>in</strong>ear regression <strong>and</strong> non-l<strong>in</strong>ear regression with<br />

normal errors <strong>and</strong> arbitrary variance function. These give rise to three of the four<br />

packages <strong>in</strong>cluded <strong>in</strong> hoa, namely, <strong>in</strong> order, cond, marg <strong>and</strong> nlreg. A fourth<br />

packaged, called sampl<strong>in</strong>g, <strong>in</strong>cludes a Metropolis-Hast<strong>in</strong>gs sampler which can<br />

be used to simulate from the conditional distribution of the higher order statistics<br />

considered <strong>in</strong> marg.

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