Coefficient intervals use the cold-multistart bootstrap percentile method
(validated to nominal coverage). The interval for alpha is a
profile-likelihood interval: first-order by default (it covers about 0.90 to
0.94 in simulations from the CPB, with its misses on the upper side; see
calibrate_alpha() for the reason), and calibrated by parametric bootstrap
when the fit went through calibrate_alpha().
Usage
# S3 method for class 'cpb'
confint(object, parm, level = 0.95, ...)