sion model. For the <code>calibrate</code>
  function, the object is a named list, where the names identify factor
  variables in <code>dframe</code>.  Each element of the list is a
  named vector containing the population total for each level of the
  associated factor variable.  For the <code>postStratify</code> function, the
  object is either a data frame, table, or xtabs object that provides the
  population total for all combinations of selected factor variables in the
  <code>dframe</code> data frame