ergmTerm-levels-not-first.R

#' @note To include all attribute values is usually not a good idea, because
#'   the sum of all such statistics equals the number of edges and hence a linear
#'   dependency would arise in any model also including \code{edges}. The default,
#'   \code{levels=-1}, is therefore to omit the first (in lexicographic order)
#'   attribute level. To include all levels, pass either \code{levels=TRUE}
#'   (i.e., keep all levels) or \code{levels=NULL} (i.e., do not filter levels).