Covariance of the regression coefficients

Usage

# S3 method for class 'zibellreg'
vcov(object, ...)

Arguments

object: an object of the class bellreg
...: further arguments passed to or from other methods.

Value

the variance-covariance matrix associated with the regression coefficients.

Examples

# \donttest{
data(cells)
fit <- zibellreg(cells ~ smoker + gender|smoker + gender, data = cells)
vcov(fit)
#>             (Intercept)      smoker      gender (Intercept)      smoker
#> (Intercept)  0.71424020 -0.66641139 -0.16297829  0.08680295 -0.06938664
#> smoker      -0.66641139  0.67787285  0.11230074 -0.07510725  0.07904856
#> gender      -0.16297829  0.11230074  0.17693895 -0.03595005  0.02389749
#> (Intercept)  0.08680295 -0.07510725 -0.03595005  0.03235207 -0.02221881
#> smoker      -0.06938664  0.07904856  0.02389749 -0.02221881  0.03364093
#> gender      -0.05319216  0.03933048  0.04235068 -0.02586416  0.01346733
#>                  gender
#> (Intercept) -0.05319216
#> smoker       0.03933048
#> gender       0.04235068
#> (Intercept) -0.02586416
#> smoker       0.01346733
#> gender       0.03150092
# }