Hi,

Can anyone tell me how to extract an AR(1) parameter from an lme model?

Here is a summary of the model:

> summary(WAElme.modAR1)
Linear mixed-effects model fit by maximum likelihood
 Data: WAElmeData
        AIC       BIC   logLik
  -103.6577 -83.43384 57.82883

Random effects:
 Formula: ~1 | WBIC
        (Intercept)  Residual
StdDev:  0.08148838 0.2578487

Correlation Structure: ARMA(1,0)
 Formula: ~year | WBIC
 Parameter estimate(s):
     Phi1
0.7262637
Fixed effects: log10pe ~ year + area
                Value  Std.Error  DF  t-value p-value
(Intercept)  3.468126 0.08024473 203 43.21937  0.0000
year        -0.009656 0.00491928 203 -1.96292  0.0510
area         0.276664 0.04673097   9  5.92035  0.0002
 Correlation:
     (Intr) year
year -0.823
area -0.034  0.065

Standardized Within-Group Residuals:
         Min           Q1          Med           Q3          Max
-3.182366526 -0.526080732 -0.002701109  0.573640884  2.406525772

Number of Observations: 215
Number of Groups: 11

I can print the value of the phi parameter as follows:

> WAElme.modAR1$modelStruct$corStruct
Correlation structure of class corARMA representing
     Phi1
0.7262637

but I am not able to use this in further calculations.  Can anyone tell me how to extract this as a scalar for use in further calculations?

Thank you,
Paul Rasmussen
Wisconsin DNR






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