Tobit Regression
Fitting and testing tobit regression models for censored data.
tobit(formula, left = 0, right = Inf, dist = "gaussian",
subset = NULL, data = list(), ...)formula |
a symbolic description of a regression model of type
|
left |
left limit for the censored dependent variable |
right |
right limit for the censored dependent variable |
dist |
assumed distribution for the dependent variable |
subset |
a specification of the rows to be used. |
data |
a data frame containing the variables in the model. |
... |
further arguments passed to |
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.
An object of class "tobit" inheriting from class "survreg".
Greene, W.H. (2003). Econometric Analysis, 5th edition. Upper Saddle River, NJ: Prentice Hall.
Tobin, J. (1958). Estimation of Relationships for Limited Dependent Variables. Econometrica, 26, 24–36.
data("Affairs")
## from Table 22.4 in Greene (2003)
fm.tobit <- tobit(affairs ~ age + yearsmarried + religiousness + occupation + rating,
data = Affairs)
fm.tobit2 <- tobit(affairs ~ age + yearsmarried + religiousness + occupation + rating,
right = 4, data = Affairs)
summary(fm.tobit)
summary(fm.tobit2)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.