Error(s) in re-building vignettes:
  ...
--- re-building ‘DIF_vignette.Rmd’ using rmarkdown

Attaching package: 'dplyr'

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

no column `person_id` provided, automatically generating unique person id's
Quitting from lines 45-58 (DIF_vignette.Rmd) 
Error: processing vignette 'DIF_vignette.Rmd' failed with diagnostics:
there is no package called 'Cairo'
--- failed re-building ‘DIF_vignette.Rmd’

--- re-building ‘Dexter.Rmd’ using rmarkdown

Attaching package: 'dplyr'

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

Quitting from lines 124-125 (Dexter.Rmd) 
Error: processing vignette 'Dexter.Rmd' failed with diagnostics:
there is no package called 'Cairo'
--- failed re-building ‘Dexter.Rmd’

--- re-building ‘Equating.Rmd’ using rmarkdown
Quitting from lines 59-101 (Equating.Rmd) 
Error: processing vignette 'Equating.Rmd' failed with diagnostics:
there is no package called 'Cairo'
--- failed re-building ‘Equating.Rmd’

--- re-building ‘Plausible_Values.Rmd’ using rmarkdown
Quitting from lines 86-89 (Plausible_Values.Rmd) 
Error: processing vignette 'Plausible_Values.Rmd' failed with diagnostics:
there is no package called 'Cairo'
--- failed re-building ‘Plausible_Values.Rmd’

--- re-building ‘Profile-plots.Rmd’ using rmarkdown
no column `person_id` provided, automatically generating unique person id's
Quitting from lines 46-52 (Profile-plots.Rmd) 
Error: processing vignette 'Profile-plots.Rmd' failed with diagnostics:
there is no package called 'Cairo'
--- failed re-building ‘Profile-plots.Rmd’

--- re-building ‘Test_Individual_differences.Rmd’ using rmarkdown
Quitting from lines 51-53 (Test_Individual_differences.Rmd) 
Error: processing vignette 'Test_Individual_differences.Rmd' failed with diagnostics:
there is no package called 'Cairo'
--- failed re-building ‘Test_Individual_differences.Rmd’

SUMMARY: processing the following files failed:
  ‘DIF_vignette.Rmd’ ‘Dexter.Rmd’ ‘Equating.Rmd’ ‘Plausible_Values.Rmd’
  ‘Profile-plots.Rmd’ ‘Test_Individual_differences.Rmd’

Error: Vignette re-building failed.
Execution halted