gls
fit. The semi-variogram values are calculated for
pairs of residuals within the same group level, if a grouping factor
is present. If collapse
is different from "none"
, the
individual semi-variogram values are collapsed using either a robust
estimator (robust = TRUE
) defined in Cressie (1993), or the
average of the values within the same distance interval. The
semi-variogram is useful for modeling the error term correlation
structure.## S3 method for class 'gls':
Variogram(object, distance, form, resType, data,
na.action, maxDist, length.out, collapse, nint, breaks,
robust, metric, \dots)
variog
and dist
representing,
respectively, the semi-variogram values and the corresponding
distances. If the semi-variogram values are collapsed, an extra
column, n.pairs
, with the number of residual pairs used in each
semi-variogram calculation, is included in the returned data frame. If
object
includes a corSpatial
element, a data frame with
its corresponding semi-variogram is included in the returned value, as
an attribute "modelVariog"
. The returned value inherits from
class Variogram
.gls
,
Variogram
,
Variogram.default
,
Variogram.lme
,
plot.Variogram
fm1 <- gls(weight ~ Time * Diet, BodyWeight)
Variogram(fm1, form = ~ Time | Rat)[1:10,]
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