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.