corAR1(value, form, fixed)
value
| the value of the lag 1 autocorrelation, which must be between -1 and 1. Defaults to 0 (no autocorrelation). |
form
|
a one sided formula of the form ~ t , or code{~ t |
g}, specifying a time covariate t and, optionally, a
grouping factor g . A covariate for this correlation structure
must be integer valued. When a grouping factor is present in
form , the correlation structure is assumed to apply only
to observations within the same grouping level; observations with
different grouping levels are assumed to be uncorrelated. Defaults to
~ 1 , which corresponds to using the order of the observations
in the data as a covariate, and no groups.
|
fixed
|
an optional logical value indicating whether the
coefficients should be allowed to vary in the optimization, or kept
fixed at their initial value. Defaults to FALSE , in which case
the coefficients are allowed to vary.
|
corAR1
class,
representing an autocorrelation structure of order 1. Objects
created using this constructor need to be later initialized using the
appropriate initialize
method.corAR1
, representing an autocorrelation
structure of order 1.initialize.corStruct
library(lme) ## covariate is observation order and grouping factor is Mare cs1 <- corAR1(0.2, form = ~ 1 | Mare)