Mroz87: U.S. Women's Labor Force Participation
In sampleSelection: Sample Selection Models

Description Usage Format Source Examples

The Mroz87 data frame contains data about 753 married women. These data are collected within the "Panel Study of Income Dynamics" (PSID). Of the 753 observations, the first 428 are for women with positive hours worked in 1975, while the remaining 325 observations are for women who did not work for pay in 1975. A more complete discussion of the data is found in Mroz (1987), Appendix 1.

1	data(Mroz87)

This data frame contains the following columns:

lfp: Dummy variable for labor-force participation.
hours: Wife's hours of work in 1975.
kids5: Number of children 5 years old or younger.
kids618: Number of children 6 to 18 years old.
age: Wife's age.
educ: Wife's educational attainment, in years.
wage: Wife's average hourly earnings, in 1975 dollars.
repwage: Wife's wage reported at the time of the 1976 interview.
hushrs: Husband's hours worked in 1975.
husage: Husband's age.
huseduc: Husband's educational attainment, in years.
huswage: Husband's wage, in 1975 dollars.
faminc: Family income, in 1975 dollars.
mtr: Marginal tax rate facing the wife.
motheduc: Wife's mother's educational attainment, in years.
fatheduc: Wife's father's educational attainment, in years.
unem: Unemployment rate in county of residence, in percentage points.
city: Dummy variable = 1 if live in large city, else 0.
exper: Actual years of wife's previous labor market experience.
nwifeinc: Non-wife income.
wifecoll: Dummy variable for wife's college attendance.
huscoll: Dummy variable for husband's college attendance.

Mroz, T. A. (1987) The sensitivity of an empirical model of married women's hours of work to economic and statistical assumptions. Econometrica 55, 765–799.

PSID Staff, The Panel Study of Income Dynamics, Institute for Social ResearchPanel Study of Income Dynamics, University of Michigan, https://psidonline.isr.umich.edu.

## Wooldridge( 2003 ): example 17.5, page 590
data( Mroz87 )
# Two-step estimation
summary( heckit( lfp ~ nwifeinc + educ + exper + I( exper^2 ) + age +
   kids5 + kids618, log( wage ) ~ educ + exper + I( exper^2 ), Mroz87,
   method = "2step" ) )

Loading required package: maxLik
Loading required package: miscTools

Please cite the 'maxLik' package as:
Henningsen, Arne and Toomet, Ott (2011). maxLik: A package for maximum likelihood estimation in R. Computational Statistics 26(3), 443-458. DOI 10.1007/s00180-010-0217-1.

If you have questions, suggestions, or comments regarding the 'maxLik' package, please use a forum or 'tracker' at maxLik's R-Forge site:
https://r-forge.r-project.org/projects/maxlik/
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Tobit 2 model (sample selection model)
2-step Heckman / heckit estimation
753 observations (325 censored and 428 observed)
15 free parameters (df = 739)
Probit selection equation:
             Estimate Std. Error t value Pr(>|t|)    
(Intercept)  0.270077   0.508593   0.531  0.59556    
nwifeinc    -0.012024   0.004840  -2.484  0.01320 *  
educ         0.130905   0.025254   5.183 2.81e-07 ***
exper        0.123348   0.018716   6.590 8.34e-11 ***
I(exper^2)  -0.001887   0.000600  -3.145  0.00173 ** 
age         -0.052853   0.008477  -6.235 7.61e-10 ***
kids5       -0.868328   0.118522  -7.326 6.21e-13 ***
kids618      0.036005   0.043477   0.828  0.40786    
Outcome equation:
              Estimate Std. Error t value Pr(>|t|)    
(Intercept) -0.5781032  0.3050062  -1.895  0.05843 .  
educ         0.1090655  0.0155230   7.026 4.83e-12 ***
exper        0.0438873  0.0162611   2.699  0.00712 ** 
I(exper^2)  -0.0008591  0.0004389  -1.957  0.05068 .  
Multiple R-Squared:0.1569,	Adjusted R-Squared:0.149
   Error terms:
              Estimate Std. Error t value Pr(>|t|)
invMillsRatio  0.03226    0.13362   0.241    0.809
sigma          0.66363         NA      NA       NA
rho            0.04861         NA      NA       NA
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