[ADMB Users] Integrating R and ADMB to generalize TPL files
dave fournier
davef at otter-rsch.com
Wed Nov 7 16:03:34 PST 2012
On 12-11-07 11:32 AM, Ben Bolker wrote:
Well I don't recall getting personal. I was referring to
what I feel are problems with the design of R.
Anyway it apears that you don't seem to have the right model here.
This should be pretty simple. One has 192 random effects. all I did
was to use 3 different parameters for the standard deviations of the random
effects. sd1 for obs 1-64 sd2 for obs 65-128 and sd3 for obs 129-192.
You seem to have something completely different. the par file is
# Number of parameters = 8 Objective function value = 285.193 Maximum
gradient component = 6.97992e-05
# pz:
0.000100000000000
# beta:
-1.68901008026 -0.817412602915 -4.06986974939 6.84143453412
# tmpL:
-0.114257455234 -0.256577632335 -0.00360094954491
# tmpL1:
0.000100000000000 0.000100000000000 0.000100000000000
# log_alpha:
1.36928124319
so the fit is much worse.
> On 12-11-07 01:17 PM, dave fournier wrote:
>> >But that is not right. The model is to assume that the
>> >random effects in different time periods are independent and that their
>> >variances are different. You can do this by figuring out what the
>> >correct covariance is for the current design matrix or by
>> >writing the model properly which is trivial to do in ADMB. As usual it
>> >is the R interface and these silly design matrices which introduces the
>> >problem.
>> >_______________________________________________
>> >Users mailing list
>> >Users at admb-project.org
>> >http://lists.admb-project.org/mailman/listinfo/users
> Just to continue this a little bit:
>
> If I do this:
>
> l2 <- read.csv("bigelow_dat.txt")
>
> ## unnecessary picture
> library(ggplot2)
> ggplot(l2,aes(factor(time),snag))+
> geom_dotplot(binaxis="y",stackdir="center")+
> facet_wrap(~Ecozone+time,scale="free_x")
>
> with(l2,table(table(plot))) ## check exp. design: 3 samples per plot
> with(l2,table(table(plot,time))) ## check exp. design: 1 sample per
> plot/time
> l2$ftime <- factor(l2$time) ## factor-ize time
>
> library(glmmADMB)
> ## note zero-inflation is FALSE/off throughout (default)
> g1 <- glmmadmb(formula = snag ~ ftime + Ecozone + (1 | plot), data = l2,
> family = "nbinom1")
> VarCorr(g1)
> log(sqrt(VarCorr(g1)[[1]])) ## log std. dev. =0.4315505 ## matches DF
> logLik(g1)
> ## 'log Lik.' -255.758 (df=6) ## matches DF
> coef(g1)
> ## (Intercept) ftime2 ftime3 EcozoneW
> ## -0.7635323 -0.5884655 -0.6037133 1.2493021
>
> ## ?? The fixed effects don't match DF results: did he orthogonalize the
> design matrix ... ?
> ## never mind
>
> ## besides being the wrong model, this fails on my system (32-bit Linux)
> try(g2 <- glmmadmb(formula = snag ~ ftime + Ecozone + (ftime | plot),
> data = l2, family = "nbinom1"))
>
> ## this works and is (I think) the right model ...
> g3 <- glmmadmb(formula = snag ~ ftime + Ecozone + (ftime-1 | plot), data
> = l2, family = "nbinom1",
> save.dir="glmmadmb_tmp")
> ## the Z matrix looks like I think it should (an indicator variable for
> time period)
> VarCorr(g3)
>
> ## Random effects:
> ## Structure: Diagonal matrix
> ## Group=plot
> ## Variance StdDev
> ## time1 0.7957 0.8920
> ## time2 0.5986 0.7737
> ## time3 0.9928 0.9964
>
> log(sqrt(diag(VarCorr(g3)[[1]])))
> ## ftime1 ftime2 ftime3
> ## -0.11426024 -0.25658084 -0.00360295
>
> ## This doesn't match DF: he gets the log-sd of the variances as
>
> ## tmpL:
> ## 0.352458239856 0.489012745656 0.496221176099
>
> ## i.e. increasing from period 1 to periods 2 and 3
>
> For the overdispersion model (which I haven't run yet -- glmmADMB is not
> flexible enough) -- DF gets
>
> # tmpL:
> 0.436593520224
> # tmpL1:
> 0.000100000000000
> # log_alpha:
> 0.826338727816 0.0677913813376 0.657156858701
>
> i.e. the log-sd among plots (tmpL) is about the same as before, and
> log_alpha is the log of the NB scale parameter. This suggests*lower*
> variance (at least when scaled by the mean) in the second period,
> *higher* variance in the first period -- which seems (??) to match the
> (ftime-1|plot) glmmADMB results rather than the DF results (??)
>
> I'd rather be arguing over what the data say than over whose tools are
> better
> or worse, or who's an idiot. I'm happy to concede that I'm an idiot, so we
> can get that over right at the beginning ...
>
> cheers
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