wooldrige_tobit

require(AER)

## Loading required package: AER

## Warning: package 'AER' was built under R version 3.6.3

## Loading required package: car

## Warning: package 'car' was built under R version 3.6.3

## Loading required package: carData

## Warning: package 'carData' was built under R version 3.6.1

## Loading required package: lmtest

## Warning: package 'lmtest' was built under R version 3.6.3

## Loading required package: zoo

## Warning: package 'zoo' was built under R version 3.6.3

## 
## Attaching package: 'zoo'

## The following objects are masked from 'package:base':
## 
##     as.Date, as.Date.numeric

## Loading required package: sandwich

## Warning: package 'sandwich' was built under R version 3.6.3

## Loading required package: survival

require(wooldridge)

## Loading required package: wooldridge

## Warning: package 'wooldridge' was built under R version 3.6.3

require(npsf)

## Loading required package: npsf

## Warning: package 'npsf' was built under R version 3.6.3

## Loading required package: Formula

## Loading required package: randtoolbox

## Warning: package 'randtoolbox' was built under R version 3.6.2

## Loading required package: rngWELL

## Warning: package 'rngWELL' was built under R version 3.6.2

## This is randtoolbox. For an overview, type 'help("randtoolbox")'.

## Loading required package: sfsmisc

## Warning: package 'sfsmisc' was built under R version 3.6.3

data(mroz)
names(mroz)

##  [1] "inlf"     "hours"    "kidslt6"  "kidsge6"  "age"      "educ"    
##  [7] "wage"     "repwage"  "hushrs"   "husage"   "huseduc"  "huswage" 
## [13] "faminc"   "mtr"      "motheduc" "fatheduc" "unem"     "city"    
## [19] "exper"    "nwifeinc"

fm.tobit <- tobit(hours~nwifeinc+educ+exper+I(exper^2)+age+kidslt6+kidsge6,
data = mroz)
summary(fm.tobit)

## 
## Call:
## tobit(formula = hours ~ nwifeinc + educ + exper + I(exper^2) + 
##     age + kidslt6 + kidsge6, data = mroz)
## 
## Observations:
##          Total  Left-censored     Uncensored Right-censored 
##            753            325            428              0 
## 
## Coefficients:
##               Estimate Std. Error z value Pr(>|z|)    
## (Intercept)  965.30528  446.43614   2.162 0.030599 *  
## nwifeinc      -8.81424    4.45910  -1.977 0.048077 *  
## educ          80.64561   21.58324   3.736 0.000187 ***
## exper        131.56430   17.27939   7.614 2.66e-14 ***
## I(exper^2)    -1.86416    0.53766  -3.467 0.000526 ***
## age          -54.40501    7.41850  -7.334 2.24e-13 ***
## kidslt6     -894.02174  111.87804  -7.991 1.34e-15 ***
## kidsge6      -16.21800   38.64139  -0.420 0.674701    
## Log(scale)     7.02289    0.03706 189.514  < 2e-16 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Scale: 1122 
## 
## Gaussian distribution
## Number of Newton-Raphson Iterations: 4 
## Log-likelihood: -3819 on 9 Df
## Wald-statistic: 253.9 on 7 Df, p-value: < 2.22e-16