This term adds multiple network
statistics to the model, one for each of (a subset of) the unique
values of the
attr attribute (or each combination of the
attributes given). Each of these statistics gives the number of
times a node with that attribute or those attributes appears as the
terminal node of a directed tie.
For an analogous term for quantitative vertex attributes, see
# binary: nodeifactor(attr, base=1, levels=-1) # valued: nodeifactor(attr, base=1, levels=-1, form="sum")
quantitative attribute (see Specifying Vertex attributes and Levels (
this optional argument controls which levels of the attribute
attributes and Levels (
character how to aggregate tie values in a valued ERGM
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
edges. The default,
levels=-1, is therefore to omit the first (in lexicographic order)
attribute level. To include all levels, pass either
(i.e., keep all levels) or
levels=NULL (i.e., do not filter levels).
base is retained for backwards compatibility and may be
removed in a future version. When both
levels are passed,
ergmTerm for index of model terms currently visible to the package.
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