qqnorm.lme {nlme} | R Documentation |

Diagnostic plots for assessing the normality of residuals and random
effects in the linear mixed-effects fit are obtained. The
`form`

argument gives considerable flexibility in the type of
plot specification. A conditioning expression (on the right side of a
`|`

operator) always implies that different panels are used for
each level of the conditioning factor, according to a Trellis
display.

## S3 method for class 'lme': qqnorm(y, form, abline, id, idLabels, grid, ...)

`y` |
an object inheriting from class `lme` , representing
a fitted linear mixed-effects model or from class `lmList` ,
representing a list of `lm` objects, or from class `lm` ,
representing a fitted linear model, or from class `nls` ,
representing a nonlinear least squares fitted model. |

`form` |
an optional one-sided formula specifying the desired type of
plot. Any variable present in the original data frame used to obtain
`y` can be referenced. In addition, `y` itself
can be referenced in the formula using the symbol
`"."` . Conditional expressions on the right of a `|`
operator can be used to define separate panels in a Trellis
display. The expression on the right hand side of `form` and to
the left of a `|` operator must evaluate to a residuals vector,
or a random effects matrix. Default is `~ resid(., type = "p")` ,
corresponding to a normal plot of the standardized residuals
evaluated at the innermost level of nesting. |

`abline` |
an optional numeric value, or numeric vector of length two. If given as a single value, a horizontal line will be added to the plot at that coordinate; else, if given as a vector, its values are used as the intercept and slope for a line added to the plot. If missing, no lines are added to the plot. |

`id` |
an optional numeric value, or one-sided formula. If given as
a value, it is used as a significance level for a two-sided outlier
test for the standardized residuals (random effects). Observations with
absolute standardized residuals (random effects) greater than the
1 - value/2 quantile of the standard normal distribution are
identified in the plot using `idLabels` . If given as a one-sided
formula, its right hand side must evaluate to a logical, integer, or
character vector which is used to identify observations in the
plot. If missing, no observations are identified. |

`idLabels` |
an optional vector, or one-sided formula. If given as a
vector, it is converted to character and used to label the
observations identified according to `id` . If given as a
one-sided formula, its right hand side must evaluate to a vector
which is converted to character and used to label the identified
observations. Default is the innermost grouping factor. |

`grid` |
an optional logical value indicating whether a grid should
be added to plot. Default is `FALSE` . |

`...` |
optional arguments passed to the Trellis plot function. |

a diagnostic Trellis plot for assessing normality of residuals or random effects.

Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu

## Not run: fm1 <- lme(distance ~ age, Orthodont, random = ~ age | Subject) # normal plot of standardized residuals by gender qqnorm(fm1, ~ resid(., type = "p") | Sex, abline = c(0, 1)) # normal plots of random effects qqnorm(fm1, ~ranef(.)) ## End(Not run)

[Package *nlme* version 3.1-57 Index]