Hi all,
I have mark-recapture distance-sampling aerial survey data temporally stratified within a region of interest. Specifically, there are 12 replicate surveys within the 1 region of interest. Each replicate survey has 4 transects.
I've identified the following mrds ddf() model:
MRDS.6a=ddf(
dsmodel=~mcds(key="hn",formula=~side+obsname),
mrmodel=~glm(~obsname + size),
data=survey.data,
method="io",
meta.data=list(binned=TRUE,point=FALSE,width=300,
breaks=c(0,50,100,200,300)))
I want to derive abundance and variance estimates with respect to each replicate survey using the ddf() model outlined above. I use dht2():
FG.roo.MRDS <- dht2(ddf = MRDS.6a,
flatfile = flatfile.mrds,
stratification = "effort_sum",
strat_formula = ~Rep,
er_est = "R2",
ci_width = 0.95)
my flatfile contains all five essential columns + the three covariates used in the mrds model. The error I can't get past when running the dht2() model is:
Error in if (ddf$ds$aux$point) "point" else "line" :
argument is of length zero
I'm uncertain about where or how to actually specify this information when using ddf(). There are two things I could think of that could be causing the error...
1. My ddf() model does have a similar ?'slot'? but it's address is:
MRDS.6a[["ds"]][["ds"]][["aux"]][["point"]]
2. There are duplicate observations in the flatfile (because observer name is a covariate and it is a mark-recapture model).
All suggestions much appreciated. Thanks in advance!
Evan