Computes boundary points of a two-dimensional confidence region for model parameters.

## Usage

```
# S4 method for EL
confreg(object, parm, level = 0.95, cv = NULL, npoints = 50L, control = NULL)
```

## Arguments

- object
An object that inherits from EL.

- parm
A specification of which parameters are to be given a confidence region, either a vector of numbers or a vector of names. It must be a vector of length two of the form

`c(x, y)`

. If missing, the first two parameter in`object`

are considered.- level
A single numeric for the confidence level required. Defaults to

`0.95`

. It is ignored if`cv`

is non-`NULL`

.- cv
A single numeric for the critical value for calibration of empirical likelihood ratio statistic. Defaults to NULL and set to

`qchisq(level, 2L)`

. It must be compatible with the`th`

value in`control`

.- npoints
A single integer for the number of boundary points to compute. Defaults to

`50`

.- control
An object of class ControlEL constructed by

`el_control()`

. Defaults to`NULL`

and inherits the`control`

slot in`object`

.

## Value

An object of class ConfregEL.

## References

Owen A (1990).
``Empirical Likelihood Ratio Confidence Regions.''
*The Annals of Statistics*, **18**(1), 90--120.
doi:10.1214/aos/1176347494
.