zoib (version 1.1)

GasolineYield: Gasoline Yields Data

Description

Proportion of crude oil converted to gasoline after distillation and fractionation.

Usage

data(GasolineYield)

Details

The Gasoline Yields Data is a subset of the data GasolineYield in R package "betareg". Refer to the detailed description in R package "betareg".

References

Liu, F. and Kong, Y. (2015). ZOIB: an R Package for Bayesian Inferences in Beta and Zero One Inflated Beta Regression Models, submitted Liu, F. and Li, Q. (2014) A Bayesian Model for Joint Analysis of Multivariate Repeated Measures and Time to Event Data in Crossover Trials, Statistical Methods in Medical Research, doi: 10.1177/0962280213519594 Cribari-Neto F. and Zeileis A. (2010), Beta Regression in R. Journal of Statistical Software, 34(2):1-24

Examples

library(zoib)
  data("GasolineYield", package = "zoib")
  
  #################################################
	#  fixed effects zoib with 
  #  batch as a 10-level qualitative variable
  ################################################

  eg.fixed <- zoib(yield ~ temp + as.factor(batch)| 1, data=GasolineYield,
                 joint = FALSE,  random = 0, EUID = 1:nrow(d),
                 zero.inflation = FALSE, one.inflation = FALSE,
                 n.iter = 1100, n.thin = 5, n.burn=100)
  # yieds 400 posterior draws (200 per chain) on the parameters of interest
  
  # posterior draws of the regression coefficients
  coeff <- mcmc(eg.fixed$coef)
	traceplot(coeff)
	autocorr.plot(coeff, lag.max=5)
	check.psrf(coeff)
	summ1 <- summary(coeff)
     
  # Design Matrix: Xb, Xd, Xb0, Xb1
  eg.fixed$Xb; eg.fixed$Xd;  eg.fixed$Xb0; eg.fixed$Xb1  
  
  # Posterior predictive values of Y
  ypred = rbind(eg.fixed$ypred[[1]],eg.fixed$ypred[[2]])
  post.mean= apply(ypred,2,mean); 
  plot(GasolineYield$yield, post.mean, col='blue',pch=2); 
  abline(0,1,col='red')
  
  ######################################################
  #  mixed effects zoib with batch as a random variable
  #####################################################
  eg.random <- zoib(yield ~ temp | 1 | 1, data=GasolineYield,
                  joint = FALSE, random=1, EUID=GasolineYield$batch,
                  zero.inflation = FALSE, one.inflation = FALSE,
                  n.iter=3200, n.thin=15, n.burn=200)

  # check convergence on the regression coefficients
  sample2 <- eg.random$coeff
  traceplot(sample2)
  autocorr.plot(sample2) 
  check.psrf(coeff)
  summary(mcmc(sample2))

  # predicted y 
  ypred = rbind(eg.random$ypred[[1]],eg.random$ypred[[2]])
  post.mean= apply(ypred,2,mean); 
  plot(GasolineYield$yield, post.mean, col='blue',pch=2); 
  abline(0,1,col='red')