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User's Guide to lqa - LMU

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REFERENCES 22<br />

control<br />

... further arguments<br />

list of control parameters as returned by <strong>lqa</strong>.control(). See the<br />

<strong>lqa</strong> manual (Ulbricht, 2010a) for details.<br />

This function plots the coefficient build-ups for a given dimension of your tuning parameter(s).<br />

The argument lambdaseq can be omitted. In this case a default sequence<br />

R> lambdaseq plot.<strong>lqa</strong> (y, x, family = binomial (), penalty.family = fused.lasso,<br />

+ offset.values = c (NA, 0.01), add.MLE = FALSE)<br />

The corresponding plot is given in Figure 1. Note that the grouping effect does not<br />

cover x 3 . This is due <strong>to</strong> the small weight λ 2 = 0.01 on the second penalty term that is<br />

responsible for the fusion of correlated regressors. Note that the grouping effect among<br />

x 1 and x 2 is kept all the time. Furthermore, the relevance of the regressors is recognized<br />

as x 4 is selected <strong>to</strong> join the active set at last.<br />

References<br />

Bondell, H. D. and B. J. Reich (2008). Simultaneous regression shrinkage, variable selection<br />

and clustering of predic<strong>to</strong>rs with oscar. Biometrics 64, 115–123.<br />

Chambers, J. (1998). Programming with Data. A <strong>Guide</strong> <strong>to</strong> the S Language. New York:<br />

Springer.<br />

Fahrmeir, L., T. Kneib, and S. Lang (2009). Regression - Modelle, Methoden und Anwendungen<br />

(2nd ed.). Berlin: Springer.<br />

Fahrmeir, L. and G. Tutz (2001). Multivariate Statistical Modelling based on Generalized<br />

Linear Models (2nd ed.). New York: Springer.<br />

Frank, I. E. and J. H. Friedman (1993). A statistical view of some chemometrics regression<br />

<strong>to</strong>ols (with discussion). Technometrics 35, 109–148.<br />

Hastie, T., R. Tibshirani, and J. H. Friedman (2009). The Elements of Statistical Learning<br />

(2nd ed.). New York: Springer.

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