v2.14.1

Bug fixes

• VarCorr could return duplicates in cases where a stan_{g}lmer model used grouping
  factors with spaces. This is now fixed.
• The pairs function now also allows with group-specific parameters
• The stan_gamm4 function works better now (see issues #136, #132)
• Fix a problem with factor levels after estimating a model via stan_lm

New features

• New model-fitting function stan_betareg (and stan_betareg.fit) that uses the same likelihoods as those supported by the betareg function in the betareg package
• New choices for priors on regression coefficients: laplace, lasso, product_normal
• The hs and hs_plus priors now have new global_df and global_scale arguments
• stan_{g}lmer models that only have group-specific intercept shifts are considerably
  faster now
• Models with Student t priors and low degrees of freedom (that are not 1, 2, or 4) may work better now due to Cornish-Fisher transformations
• Many functions for priors (e.g., normal, student_t, etc.) have gained an autoscale
  argument that defaults to TRUE and indicates that rstanarm should make internal changes to the prior based on the scales of the variables. This doesn't change previous behavior, just replaces the former mechanism for controlling this (used to be the scaled argument to the now deprecated prior_options function).
• The new compare_models function is a wrapper for loo::compare that does more extensive checking that the rstanarm models being compared are compatible
• New prior_aux argument allow specifying priors for auxiliary parameters. Previously it was only possible to set the scale for the prior on auxiliary parameters (e.g., residual sd for Gaussian, shape for Gamma, etc.). With the prior_aux argument it is now possible to use exponential, normal, student_t, or cauchy for auxiliary parameters.

Deprecated arguments

• The prior_ops argument to various model fitting functions is deprecated and the prior_options function used to specify the prior_ops argument is also depredated. The functionality of prior_options has been replaced by the autoscale argument to the functions for setting priors as well as the prior_aux argument for for the prior on the auxiliary parameter of various GLM-like models.