inst/tinytest/test-singular.R

In brglm2: Bias Reduction in Generalized Linear Models

## A Gamma example, from McCullagh & Nelder (1989, pp. 300-2)
clotting <- data.frame(
    u = c(5,10,15,20,30,40,60,80,100, 5,10,15,20,30,40,60,80,100),
    conc = c(118,58,42,35,27,25,21,19,18,69,35,26,21,18,16,13,12,12),
    lot = factor(c(rep(1, 9), rep(2, 9))))
mod <- glm(conc ~ lot*log(u) + I(2*log(u)), data = clotting, family = Gamma)

X <- model.matrix(mod)
Y <- mod$y
## brglmFit returns an error if singular.ok = TRUE
expect_error(brglm_fit(X, Y, family = Gamma(), singular.ok = FALSE),
             pattern = "singular fit encountered")
expect_true(is.na(coef(brglm_fit(X, Y, family = Gamma(), singular.ok = TRUE))["I(2 * log(u))"]))