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I am working with the R package 'zoib' for performing beta regression in R. I am trying to replicate the example included on page 41 in the paper the package authors published in The R Journal:

Lui F and Kong Y. 2015. zoib: An R Package for Bayesian Inference for Beta Regression and Zero/One Inflated Beta Regression. The R Journal 7(2)

I believe I am using the exact same data and code that they use:

library(zoib)
data("GasolineYield", package="zoib")
GasolineYield$batch <- as.factor(GasolineYield$batch)
d <- GasolineYield
eg1.fixed <- zoib(yield ~ temp + as.factor(batch) | 1, data=GasolineYield, joint=FALSE,
         random=0, EUID=1:nrow(d), zero.inflation=F, one.inflation=F, 
         n.iter=1050, n.thin=5, n.burn=50)
sample1 <- eg1$coeff
traceplot(sample1)
autocorr.plot(sample1)
gelman.diag(sample1)

However, I am getting an error when I try to do the diagnostic plots on the samples. This is the error message:

Error in ts(seq(from = start(x), to = end(x), by = thin(x)), start = start(x),  : 
  invalid time series parameters specified

I cannot understand why the code isn't working or what I can do to fix the problem. I can trace the error to the time function which is called by zoib, and it seems like maybe it is a problem that the sample object does not have a tsp attribute, but the zoib package authors make it clear that their model output is meant to be used with coda, so I am very confused. I don't have much experience working with MCMC or time series objects, so maybe I am just missing something obvious. Can anyone explain why the example provided by the package authors is failing, and what the solution is?

SlowLoris
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1 Answers1

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I e-mailed the package author (Fang Liu) and she informed me that there was in fact a bug in the version of the package I have, but that the bug is fixed in the most recent version of zoib (Version 1.4.2). Using the most recent version, the code now works.

SlowLoris
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