was that this seemed like odd behavior, and that I ought to post it to one

of the developer lists. I posted to r-sig-mixed-models, but didn't get any

response. So, with good intentions, I decided to try posting once more, but

to this more general list.

The goal is (1) FYI, to make you aware of this issue, in case it is an

error in gls (2) For my information, in case I have made an error, in the

hope that one of you folks might be able to correct me. Thanks in advance

for your time.

The issue is in 2 parts.

(A) I've used gls to fit a model with two fixed effects and a corExp

object. By my count, this fitting process estimates 5 parameters:

(Intercept), l10area, newx, range, and nugget. With 118 total df, there

should be 118 - 5 = 113 residual df. However, the output from summary.gls

reports 115 residual degrees of freedom. Is this an error in summary or

gls, or is there an error in my count?

(B) Summary.gls reports logLik=-273.6. Using my count of 5 estimated

parameters, the AIC should be -2*(-273.6) + 2*5 = 557.2. However,

summary.gls reports an AIC of 559.2. If one works backwards from the

reported AIC of 559.2, it seems that gls believes it has estimated 6

parameters in the fitting process. Again, is this an error in gls, or an

error on my part?

Copied from R terminal:

summary(sppl.i.ex)

Generalized least squares fit by maximum likelihoodModel: all.all.rch ~ l10area + newx

Data: gtemp

AIC BIC logLik

559.167 575.7911 -273.5835

Correlation Structure: Exponential spatial correlation

Formula: ~x + y | area

Parameter estimate(s):

range nugget

15.4448835 0.3741476

Coefficients:

Value Std.Error t-value p-value

(Intercept) 7.621306 0.7648135 9.964921 0.0000

l10area 6.332931 0.5589199 11.330659 0.0000

newx 0.066535 0.0204417 3.254857 0.0015

Correlation:

(Intr) l10are

l10area -0.605

newx 0.358 -0.024

Standardized residuals:

Min Q1 Med Q3 Max

-3.0035983 -0.5990432 -0.2226852 0.5113270 2.4444263

Residual standard error: 2.820337

Degrees of freedom: 118 total; 115 residual

Tim Handley

Fire Effects Monitor

Santa Monica Mountains National Recreation Area

401 W. Hillcrest Dr.

Thousand Oaks, CA 91360

805-370-2347