# ddf.trial.fi: Mark-Recapture Analysis of Trial Configuration - FI In mrds: Mark-Recapture Distance Sampling

 ddf.trial.fi R Documentation

## Mark-Recapture Analysis of Trial Configuration - FI

### Description

Mark-Recapture Analysis of Trial Observer Configuration with Full Independence

### Usage

``````## S3 method for class 'trial.fi'
ddf(
dsmodel = NULL,
mrmodel,
data,
method,
meta.data = list(),
control = list(),
call = ""
)
``````

### Arguments

 `dsmodel` not used `mrmodel` mark-recapture model specification `data` analysis dataframe `method` analysis method; only needed if this function called from `ddf.trial` `meta.data` list containing settings controlling data structure `control` list containing settings controlling model fitting `call` original function call used to call `ddf`

### Details

The mark-recapture data derived from a trial observer distance sampling survey can be used to derive a conditional detection function (p_1(y)) for observer 1 based on trials (observations) from observer 2. It is a conditional detection function because detection probability for observer 1 is based on seeing or not seeing observations made by observer 2. Thus, p_1(y) is estimated by p_1|2(y). If detections by the observers are independent (full independence) then p_1(y)=p_1|2(y) for each distance y. In fitting the detection functions the likelihood given by eq 6.12 or 6.17 in Laake and Borchers (2004) is used. That analysis does not require the usual distance sampling assumption that perpendicular distances are uniformly distributed based on line placement that is random relative to animal distribution. However, that assumption is used in computing predicted detection probability which is averaged based on a uniform distribution (see eq 6.13 of Laake and Borchers 2004).

For a complete description of each of the calling arguments, see `ddf`. The argument `model` in this function is the same as `mrmodel` in `ddf`. The argument `dataname` is the name of the dataframe specified by the argument `data` in `ddf`. The arguments `control`,`meta.data`,and `method` are defined the same as in `ddf`.

### Value

result: a trial.fi model object

Jeff Laake

### References

Laake, J.L. and D.L. Borchers. 2004. Methods for incomplete detection at distance zero. In: Advanced Distance Sampling, eds. S.T. Buckland, D.R.Anderson, K.P. Burnham, J.L. Laake, D.L. Borchers, and L. Thomas. Oxford University Press.

`ddf.trial`, `summary.trial.fi`, `coef.trial.fi`, `plot.trial.fi`, `gof.trial.fi`