survstan 0.0.1

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

survstan 0.0.2

• 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.

survstan 0.0.3

• 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.

survstan 0.0.4

• The survstan package now requires rstan version 2.26.

survstan 0.0.5

• 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.

survstan 0.0.6

• 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.

survstan 0.0.6.1

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

survstan 0.0.7

• 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.

survstan 0.0.7.1

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