This is a new term for the ergm
package
that links the graphlet structures in the network for a given graphlet orbit
with numeric node attributes.
The function ergm
is used to fit linear
exponential random graph models, in which the
probability of a given network, y, on a set of nodes
is \exp{θ *
g(y)}/c(θ), where g(y) is a vector of network
statistics for y, θ is a parameter vector of the same
length and c(θ) is the normalizing constant for the distribution.
The network statistics g(y) are entered as terms in the
function call to ergm
. The ergm
package contains
a wide range of terms. For the details on the possible
<model terms>
, see ergm-terms
.
The ergm.userterms
package provides a template for
adding new terms. The terms can be used throughout the ergm
package
and behave identically to the supplied terms.
grorbitCov(attrName, grOrbit)
The correlation between a node's graphlet degree and a numeric attribute
value can be included into an ERGM by using the grorbitCov
term. The
question that the change score function of this term answers is: what is the change
in covariance between a vector of nodal attributes and nodal orbit degrees when
an edge is changed? This term has two arguments: attrname
and grorbit
.
The attrname
is a character vector giving the name of a numeric attribute
in the network's vertex attribute list. The optional grorbit
argument is
a vector of distinct integers representing the list of graphlet orbits to include
into the ERGM model. When grorbit
is not provided, all graphlet orbits are
evaluated by default. The term adds one network statistic to the model for each
element in grorbit
. This term is defined for the 73 orbits corresponding
to graphlets with up to 5 nodes. Therefore, grorbit
accepts values between 0 and
72. Values outside this range are ignored. This term can only be used with
undirected networks.
Yaveroglu ON, Fitzhugh SM, Kurant M, Markopoulou A, Butts CT, Przulj N (2015). ergm.graphlets: A Package for ERG Modeling Based on Graphlet Properties, Journal of Statistical Software 65(12), 1-29, URL http://www.jstatsoft.org/v65/i12/.
statnet, network, ergm, ergm-terms
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