Changes in version 0.1.0                        

  - implementation of baseline hazard function approximated via
    Bernstein polynomials.
  - inclusion of piecewiese exponential distribution (currently
    available for PH, PO and YP regression models).
  - use of Matrix::nearPD function to ensure the covariance function is
    positive definite.

                Changes in version 0.0.7.1 (2024-04-12)                 

  - survfit.survstan method now returns a data.frame with the observed
    survival times and their corresponding estimated baseline survivals
    when newdata = NULL.

                 Changes in version 0.0.7 (2024-03-20)                  

  - All implemented models now can accommodate an offset variable in the
    linear predictors.
  - Implementation of Gompertz and generalized gamma (original Stacy's
    parametrization and alternative Prentice's parametrization)
    distributions.

                Changes in version 0.0.6.1 (2024-02-05)                 

  - Correcting parametrization of survival functions for AH and EH
    models.

                 Changes in version 0.0.6 (2024-01-18)                  

  - update summary output.
  - tidy.survstan method was reimplemented to follow broom stantards,
    and survstan::tidy() no long masks broom::tidy().
  - cross_time() function now allows for parallel computing.
  - reparametrization of AH model (see details in
    https://fndemarqui.github.io/survstan/).
  - implementation of extended hazard (EH) family of survival regression
    models.

                 Changes in version 0.0.5 (2023-12-18)                  

  - Inclusion of emmeans method for survstan models.
  - Implementation of gamma and Rayleigh distributions.
  - Implementation of se method for computation of standard errors.
  - Correction of covariance matrix for positive parameters.
  - Application of delta method to avoid negative lower bounds in
    confidence intervals for positive parameters.
  - Bug correction in the implementation of survival functions.

                 Changes in version 0.0.4 (2023-09-21)                  

  - The survstan package now requires rstan version 2.26.

                 Changes in version 0.0.3 (2023-08-09)                  

  - The Weibull distribution is now the default baseline distribution
    (replacing the exponential distribution in previous versions).
  - Implementation of Birnbaum-Saunders (fatigue) distribution.
  - Implementation of the function rank_models to rank survstan models
    according to their AICs.

                 Changes in version 0.0.2 (2023-06-09)                  

  - Implementation of the Yang and Prentice (YP) model for dealing with
    survival data with possibly crossing survival curves.
  - Implementation of survfit.survstan method for all implemented
    models.
  - Improvement in the output of the anova.survstan function: now the
    chosen regression model and baseline distribution are displayed in
    the ANOVA table.
  - Addition of dist argument in the model fitting functions (aftreg(),
    ahreg(), phreg(), poreg() and ypreg()) as an alternative way to
    specify the baseline distribution (for compability with the
    survival::survreg() function).
  - Addition of init argument in the model fitting functions (aftreg(),
    ahreg(), phreg(), poreg() and ypreg()) with default value equals
    to 0 to fix the initial starting values when calling the
    rstan::optimizing() function.
  - Addition of extractAIC.survstan method required in the stats::step()
    function for carrying out model selection via stepwise procedures.
  - Addition of logLik.survstan method to extract the log-likelihood
    value of a fitted model.
  - AIC.survstan method now returns a data.frame with the aic values
    along with the corresponding number of model parameters when more
    than one fit is passed to the method.
  - Addition of gastric and ipass datasets.

                 Changes in version 0.0.1 (2023-05-04)                  

  - Added a NEWS.md file to track changes to the package.