Error(s) in re-building vignettes:
--- re-building ‘clustered.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘clustered.Rmd’

--- re-building ‘correlated.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘correlated.Rmd’

--- re-building ‘double_dot_extension.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘double_dot_extension.Rmd’

--- re-building ‘longitudinal.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘longitudinal.Rmd’

--- re-building ‘missing.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘missing.Rmd’

--- re-building ‘ordinal.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
Quitting from lines 247-248 (ordinal.Rmd) 
Error: processing vignette 'ordinal.Rmd' failed with diagnostics:
object 'q1' not found
--- failed re-building ‘ordinal.Rmd’

--- re-building ‘simstudy.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
`geom_smooth()` using method = 'gam' and formula 'y ~ s(x, bs = "cs")'
--- finished re-building ‘simstudy.Rmd’

--- re-building ‘spline.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
`geom_smooth()` using method = 'gam' and formula 'y ~ s(x, bs = "cs")'
--- finished re-building ‘spline.Rmd’

--- re-building ‘survival.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘survival.Rmd’

--- re-building ‘treat_and_exposure.Rmd’ using rmarkdown
Warning in engine$weave(file, quiet = quiet, encoding = enc) :
  Pandoc (>= 1.12.3) and/or pandoc-citeproc not available. Falling back to R Markdown v1.
--- finished re-building ‘treat_and_exposure.Rmd’

SUMMARY: processing the following file failed:
  ‘ordinal.Rmd’

Error: Vignette re-building failed.
Execution halted