AICc | R Documentation |
Compute AICc for one or several fitted model objects for which a log-likelihood value can be obtained.
AICc(object, ..., k = 2)
object |
A fitted model object from |
... |
Optionally more fitted model objects. |
k |
The penalty parameter, taken to be 2. Currently not allowed to differ from 2 (needed for generic consistency). |
When comparing models fit by maximum or restricted maximum
likelihood, the smaller the AICc, the better the fit. The AICc contains
a correction to AIC for small sample sizes. The theory of
AICc requires that the log-likelihood has been maximized, and hence,
no AICc methods exist for models where estmethod
is not
"ml"
or "reml"
. Additionally, AICc comparisons between "ml"
and "reml"
models are meaningless – comparisons should only be made
within a set of models estimated using "ml"
or a set of models estimated
using "reml"
. AICc comparisons for "reml"
must
use the same fixed effects. To vary the covariance parameters and
fixed effects simultaneously, use "ml"
.
Hoeting et al. (2006) study AIC and AICc in a spatial context, using the AIC definition
-2loglik + 2(estparams)
and the AICc definition as
-2loglik + 2n(estparams) / (n - estparams - 1)
, where n
is the sample size
and estparams
is the number of estimated parameters. For "ml"
, estparams
is
the number of estimated covariance parameters plus the number of estimated
fixed effects. For "reml"
, estparams
is the number of estimated covariance
parameters.
If just one object is provided, a numeric value with the corresponding AICc.
If multiple objects are provided, a data.frame
with rows corresponding
to the objects and columns representing the number of parameters estimated
(df
) and the AICc.
stats::AIC()
stats::BIC()
spmod <- splm(z ~ water + tarp,
data = caribou,
spcov_type = "exponential", xcoord = x, ycoord = y
)
AICc(spmod)
AIC(spmod)
BIC(spmod)
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