The function `tobit`

is a convenience interface to `survreg`

(for survival regression, including censored regression) setting different
defaults and providing a more convenient interface for specification
of the censoring information.

The default is the classical tobit model (Tobin 1958, Greene 2003) assuming
a normal distribution for the dependent variable with left-censoring at 0.

Technically, the formula of type `y ~ x1 + x2 + ...`

passed to `tobit`

is simply transformed into a formula suitable for `survreg`

: This means
the dependent variable is first censored and then wrapped into a `Surv`

object containing the censoring information which is subsequently passed to
`survreg`

, e.g., `Surv(ifelse(y <= 0, 0, y), y > 0, type = "left") ~ x1 + x2 + ...`

for the default settings.