R Under development (unstable) (2026-01-18 r89306 ucrt) -- "Unsuffered Consequences"
Copyright (C) 2026 The R Foundation for Statistical Computing
Platform: x86_64-w64-mingw32/x64

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library( "sampleSelection" )
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/
> 
> try( selection( s ~ z1, y ~ x1, type = "w" ) )
Error in checkModelType(type, selection, outcome) : 
  'type' in 'selection()' must be either '2', '5', or 'teatment'
Currently w
> 
> 
> # tobit 2
> 
> try( selection( s ~ z1, y ~ x1 ) )
Error in eval(predvars, data, env) : object 's' not found
> 
> try( selection( s ~ z1, y ~ x1, type = "2" ) )
Error in eval(predvars, data, env) : object 's' not found
> 
> try( selection( "s ~ z1", y ~ x1 ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'selection' must be a formula in function 'selection()'
> 
> try( selection( "s ~ z1", y ~ x1, type = "2" ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'selection' must be a formula in function 'selection()'
> 
> try( selection( ~ z1, y ~ x1 ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'selection' must be a 2-sided formula in function 'selection()'
> 
> try( selection( ~ z1, y ~ x1, type = "2" ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'selection' must be a 2-sided formula in function 'selection()'
> 
> try( selection( s ~ z1, "y ~ x1" ) )
Error in detectModelType(selection, outcome) : 
  argument 'outcome' must be a formula or a list of formulas
> 
> try( selection( s ~ z1, "y ~ x1", type = "2" ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'outcome' must be either a formula or a list of two formulas in function 'selection()'
> 
> try( selection( s ~ z1, ~ x1 ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'outcome' must be a 2-sided formula in function 'selection()'
> 
> try( selection( s ~ z1, ~ x1, type = "2" ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'outcome' must be a 2-sided formula in function 'selection()'
> 
> try( selection( s ~ z1, list( y ~ x1, y ~ x1 ), type = "2" ) )
Error in checkModelType(type, selection, outcome) : 
  type-2 and treatment models require a single outcome
in function 'selection()'.  Currently a list of length 2
> 
> 
> # tobit 5
> 
> try( selection( s ~ z1, list( y1 ~ x1, y2 ~ x1 ) ) )
Error in eval(predvars, data, env) : object 's' not found
> 
> try( selection( s ~ z1, list( y1 ~ x1, y2 ~ x1 ), type = "5" ) )
Error in eval(predvars, data, env) : object 's' not found
> 
> try( selection( "s ~ z1", list( y1 ~ x1, y2 ~ x1 ) ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'selection' must be a formula in function 'selection()'
> 
> try( selection( ~ z1, list( y1 ~ x1, y2 ~ x1 ) ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'selection' must be a 2-sided formula in function 'selection()'
> 
> try( selection( s ~ z1, list( "y1 ~ x1", y2 ~ x1 ) ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'outcome[[1]]' must be a formula in function 'selection()'
> 
> try( selection( s ~ z1, list( ~ x1, y2 ~ x1 ) ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'outcome[[1]]' must be a 2-sided formula in
in 'selection(~x1y2 ~ x1~sz1)'
> 
> try( selection( s ~ z1, list( y1 ~ x1, "y2 ~ x1" ) ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'outcome[[2]]' must be a formula in function 'selection()'
> 
> try( selection( s ~ z1, list( y1 ~ x1, ~ x1 ) ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'outcome[[2]]' must be a 2-sided formula in function 'selection()'
> 
> try( selection( s ~ z1, y1 ~ x1, type = "5" ) )
Error in checkModelType(type, selection, outcome) : 
  type '5' selection models need dual outcomes as
a list of two formulas
> 
> try( selection( s ~ z1, "y1 ~ x1", type = "5" ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'outcome' must be either a formula or a list of two formulas in function 'selection()'
> 
> 
> # treatment effects models
> 
> try( selection( s ~ z1, y1 ~ s + x1, type = "treatment" ) )
Error in eval(predvars, data, env) : object 's' not found
> 
> try( selection( s ~ z1, y1 ~ x1, type = "treatment" ) )
Error in eval(predvars, data, env) : object 's' not found
> 
> try( selection( "s ~ z1", y1 ~ s + x1, type = "treatment" ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'selection' must be a formula in function 'selection()'
> 
> try( selection(  ~ z1, y1 ~ s + x1, type = "treatment" ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'selection' must be a 2-sided formula in function 'selection()'
> 
> try( selection( s ~ z1, "y1 ~ s + x1", type = "treatment" ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'outcome' must be either a formula or a list of two formulas in function 'selection()'
> 
> try( selection( s ~ z1, ~ s + x1, type = "treatment" ) )
Error in checkModelType(type, selection, outcome) : 
  argument 'outcome' must be a 2-sided formula in function 'selection()'
> 
> try( selection( s ~ z1, list( y1 ~ s + x1, y1 ~ s + x1 ), type = "treatment" ) )
Error in checkModelType(type, selection, outcome) : 
  type-2 and treatment models require a single outcome
in function 'selection()'.  Currently a list of length 2
> 
> 
> proc.time()
   user  system elapsed 
   1.00    0.20    1.18