R: Adjusted denomintor degress freedom for linear estimate for...

get_ddf_Lb {pbkrtest} | R Documentation

## Adjusted denomintor degress freedom for linear estimate for linear mixed model.

### Description

Get adjusted denomintor degress freedom for testing Lb=0 in a linear mixed model where L is a restriction matrix.

### Usage

    get_Lb_ddf(object, L)

    ## S3 method for class 'lmerMod'
    get_Lb_ddf(object, L)

    Lb_ddf(L, V0, Vadj)

    get_ddf_Lb(object, Lcoef)

    ## S3 method for class 'lmerMod'
    get_ddf_Lb(object, Lcoef)

    ddf_Lb(VVa, Lcoef, VV0 = VVa)

### Arguments

`object` | A linear mixed model object.
`L` | A vector with the same length as `fixef(object)` or a matrix with the same number of columns as the length of `fixef(object)`
`V0, Vadj` | Unadjusted and adjusted covariance matrix for the fixed effects parameters. Undjusted covariance matrix is obtained with `vcov()` and adjusted with `vcovAdj()`.
`Lcoef` | Linear contrast matrix
`VVa` | Adjusted covariance matrix
`VV0` | Unadjusted covariance matrix

### Value

Adjusted degrees of freedom (adjusment made by a Kenward-Roger approximation).

### Author(s)

Søren Højsgaard, sorenh@math.aau.dk

### References

Ulrich Halekoh, Søren Højsgaard (2014)., A Kenward-Roger Approximation and Parametric Bootstrap Methods for Tests in Linear Mixed Models - The R Package pbkrtest., Journal of Statistical Software, 58(10), 1-30., http://www.jstatsoft.org/v59/i09/

### See Also

`KRmodcomp`, `vcovAdj`, `model2restrictionMatrix`, `restrictionMatrix2model`

### Examples

    (fmLarge <- lmer(Reaction ~ Days + (Days|Subject), sleepstudy))
    ## removing Days
    (fmSmall <- lmer(Reaction ~ 1 + (Days|Subject), sleepstudy))
    anova(fmLarge,fmSmall)

    KRmodcomp(fmLarge, fmSmall)  ## 17 denominator df's
    get_Lb_ddf(fmLarge, c(0,1)) ## 17 denominator df's

    # Notice: The restriction matrix L corresponding to the test above
    # can be found with
    L <- model2restrictionMatrix(fmLarge, fmSmall)
    L

[Package pbkrtest version 0.4-7 Index]