npsf v0.8.0 (Release date: 2020-11-22)

* added the `exponential` cross-sectional model
* fixed various bugs

npsf v0.7.1 (Release date: 2020-06-24)

* added detailed solution to teradial
  * intendity variables for DEA (to obtain peers)

npsf v0.7.0 (Release date: 2020-06-13)

* improved the `sf` function, especially the `4comp` model
* fixed various bugs
* dropped dependence on randtoolbox and sfsmisc packages
* added flexible functions for Halton draws
  * primes
  * halton
  * rescale

npsf v0.6.0 (Release date: 2020-05-20)

* added the function `tenonradialbc` for bias correction for the Russell measure
  * smoothed homogeneous
  * subsampling heterogeneous
* added detailed solution to tenonradial
  * individual thetas and lambdas
  * intendity variables for DEA (to obtain peers)

npsf v0.5.2 (Release date: 2019-09-08)

* Fixed various bugs
* `truncreg` is made run fast

npsf v0.5.1 (Release date: 2019-04-12)

* the `4 components` model is added
* summary works for 1st and 2nd generation panel data models
* Fixed various bugs

npsf v0.4.2 (Release date: 2019-01-02)

* Fixed various bugs

npsf v0.4.1 (Release date: 2018-07-19)

* Added sf panel data models
  * In all models, user optionally
    * can make all components heteroskedastic and 
      specify the heterskedasticity function,
    * choose between normal-half-normal and
    * normal-truncated normal model, and
    * specify conditional mean function
  * 1st generation panel data models: time-invariant inefficiency
  * 2nd generation panel data models: time-variant inefficiency with
    parametric function of inefficiency evolution

npsf v0.3.1 (Release date: 2018-01-17)

* Fixed various bugs
* Own LP solver instead of glpk
* added nobs() method for objects of class 'npsf'
* added summary() method for objects of class 'npsf'
* added print() method for objects of class 'npsf'
* added vcov() method for objects of class 'npsf' 
  (relevant for function 'sf')
* added coef() method for objects of class 'npsf'
  (relevant for function 'sf')

npsf v0.2.0 (Release date: 2017-01-19)

* Fixed bugs with data preparation
* Fixed initial values for truncated regression (truncreg) estimation

npsf v0.1.9 (Release date: 2016-09-02)

* Fixed some bugs with data preparation
* Added truncated regression (truncreg) estimation with 
  lower and upper bounds (which can be specified simultaneously)

npsf v0.1.8 (Release date: 2016-07-05)

* Added nobs(), coef(), and vcov() for all relevant objects
* Added summary() and print() for all relevant objects
* Fixed some bugs with names in sf
* Fixed documentation

npsf v0.1.6 (Release date: 2015-09-20)

* Initial release of the npsf package on CRAN