New Graphlet Count Term for the 'ergm' Package – introduced under 'ergm.graphlets' package
Description
This is a new term for the ergm
package
that counts the number of graphlets in the network for a given graphlet type.
Details
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 ergmterms
.
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.
The Graphlet Count Term
graphletCount(g)

Statistics for the number of times that a graphlet appears in a network can be included in an ERGM by using the
graphletCount
term. The question that the change score function of this term answers is: how do the number of graphlets of type G_i change when an edge is flipped in the network? This term has an optional argument,g
.g
is a vector of distinct integers representing the list of graphlets to be evaluated during the estimation of model coefficients. When this argument is not provided, all graphlets are evaluated by default. The term adds one network statistic to the model for each element ing
. This term is defined for the 30 graphlets with up to 5 nodes. Therefore,g
accepts values between 0 and 29. Values outside this range are ignored.
References
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), 129, URL http://www.jstatsoft.org/v65/i12/.
See Also
statnet, network, ergm, ergmterms