[R] help about how can R compute AIC?

[Arnau Mir Torres]

Hello.

I need to know how can R compute AIC when I study a regression model?
For example, if I use these data:
   growth tannin
1     12      0
2     10      1
3      8      2
4     11      3
5      6      4
6      7      5
7      2      6
8      3      7
9      3      8
and I do
model <- lm (growth ~ tannin)
AIC(model)

R responses:
38.75990

I know the following formula to compute AIC:
AIC= -2*log-likelihood + 2*(p+1)

In my example, it would be:
AIC=-2*log-likelihood + 2*2
but I don't know how R computes log-likelihood:

logLik(model)
'log Lik.' -16.37995 (df=3)


Thanks,

Arnau.
------------------------------------------------------------
Arnau Mir Torres
Edifici A. Turmeda
Campus UIB
Ctra. Valldemossa, km. 7,5
07122 Palma de Mca.
tel: (+34) 971172987
fax: (+34) 971173003
email: arnau.mir at uib.es
URL: http://dmi.uib.es/~arnau