Error in re-building vignettes:
  ...
Loading required package: cem
Loading required package: tcltk
Loading required package: lattice

How to use CEM? Type vignette("cem")

Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in min(x, na.rm = TRUE) :
  no non-missing arguments to min; returning Inf
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in min(x, na.rm = TRUE) :
  no non-missing arguments to min; returning Inf
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in min(x, na.rm = TRUE) :
  no non-missing arguments to min; returning Inf
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in dist(data[idx2, obj$vars], method = method, p = mpower) :
  NAs introduced by coercion
Warning in min(x, na.rm = TRUE) :
  no non-missing arguments to min; returning Inf
Loading required package: Amelia
Warning in library(package, lib.loc = lib.loc, character.only = TRUE, logical.return = TRUE,  :
  there is no package called ‘Amelia’

Error: processing vignette ‘cem.Rnw’ failed with diagnostics:
 chunk 36 
Error in amelia(LeLonde, noms = c("black", "hispanic", "treated", "married",  : 
  could not find function "amelia"
Execution halted