Changes in version 1.1.0                        

  - survit function returns now a list containing two objects: time and
    surv associated with the observed survival times and their
    corresponding survival probabilities.

  - inclusion of model.matrix method

  - implementation of phpe() and phpo() functions to fit proportional
    hazards (PH) and proportional odds (PO) models.

  - implementation of anova.yppe() function to carry out likelihood
    ratio tests.

  - implemantation of AIC.yppe() function to compute AIC (Akaike
    information criterion).

  - implemantation of logLik.yppe() function to extract the
    log-likelihood value of a fitted model.

  - the YPPE package now requires rstan Version 2.26.

  - update package reference.

                 Changes in version 1.0.1 (2020-01-09)                  

  - coef() function to extract the regression coefficientes under the
    MLE approach

  - vcov() function to compute the variance-covariance matrix associated
    with the regression coefficients under the MLE approach

  - confint() function to compute the 100(1-alpha)% confidence intervals
    under the MLE approahc

  - bug fix: yppe() function now works properly if both the number of
    intervals and the time grid (n_int and rho) are passed as arguments;
    the default time grid is now computed by using all distinct observed
    failure times as the endpoints of the intervals