FLXMRrobglm {flexmix} | R Documentation

## FlexMix Driver for Robust Estimation of Generalized Linear Models

### Description

This driver adds a noise component to the mixture model which can be used to model background noise in the data. See the Compstat paper Leisch (2008) cited below for details.

### Usage

    FLXMRrobglm(formula = . ~ ., family = c("gaussian", "poisson"),
                bgw=FALSE, ...)

### Arguments

`formula` | A formula which is interpreted relative to the formula specified in the call to `flexmix` using `update.formula`. Default is to use the original `flexmix` model formula.
`family` | A character string naming a `glm` family function.
`bgw` | Logical, controls whether the parameters of the background component are fixed to multiples of location and scale of the complete data (the default), or estimated by EM with normal weights for the background (`bgw=TRUE`).
`...` | passed to `FLXMRglm`

### Value

Returns an object of class `FLXMRrobglm`.

### Note

The implementation of this model class is currently under development, and some methods like `refit` are still missing.

### Author(s)

Friedrich Leisch and Bettina Gruen

### References

Friedrich Leisch. Modelling background noise in finite mixtures of generalized linear regression models. In Paula Brito, editor, Compstat 2008-Proceedings in Computational Statistics, pages 385-396. Physica Verlag, Heidelberg, Germany, 2008. Preprint available at http://epub.ub.uni-muenchen.de/6332/.

### Examples

    ## Example from Compstat paper, see paper for detailed explanation:
    data("NPreg")
    DATA <- NPreg[,1:2]
    set.seed(3)
    DATA2 <- rbind(DATA, cbind(x=-runif(3), yn=50+runif(3)))

    ## Estimation without (f2) and with (f3) background component
    f2 <- flexmix(yn~x+I(x^2), data=DATA2, k=2)
    f3 <- flexmix(yn~x+I(x^2), data=DATA2, k=3, model=FLXMRrobglm(),
                  control=list(minprior=0))

    ## Predict on new data for plots
    x <- seq(-5,15,by=.1)
    y2 <- predict(f2, newdata=data.frame(x=x))
    y3 <- predict(f3, newdata=data.frame(x=x))

    ## f2 was estimated without background component:
    plot(yn~x, data=DATA2, pch=clusters(f2), col=clusters(f2))
    lines(x, y2$Comp.1, col=1)
    lines(x, y2$Comp.2, col=2)

    ## f3 is with background component:
    plot(yn~x, data=DATA2, pch=4-clusters(f3), col=4-clusters(f3))
    lines(x, y3$Comp.2, col=2)
    lines(x, y3$Comp.3, col=1)

[Package flexmix version 2.2-4 Index]