This page describes how to specify the reference measures (baseline distributions)
(the set of possible networks \(Y\) and the baseline weights \(h(y)\) to functions in the ergm
package. It also provides an indexed list of the references visible to the ergm's API. References can also be searched via search.ergmReferences()
, and help for an individual reference can be obtained with ergmReference?<reference>
or help("<reference>-ergmReference")
.
In an exponential-family random graph model (ERGM), the probability or density of a given network, \(y \in Y\), on a set of nodes is $$h(y) \exp[\eta(\theta) \cdot g(y)] / \kappa(\theta),$$ where \(h(y)\) is the reference distribution (particularly for valued network models), \(g(y)\) is a vector of network statistics for \(y\), \(\eta(\theta)\) is a natural parameter vector of the same length (with \(\eta(\theta)\equiv\theta\) for most terms), \(\cdot\) is the dot product, and \(\kappa(\theta)\) is the normalizing constant for the distribution. A complete ERGM specification requires a list of network statistics \(g(y)\) and (if applicable) their \(\eta(\theta)\) mappings provided by a formula of ergmTerm
s; and, optionally, sample space \(\mathcal{Y}\) and reference distribution \(h(y)\) information provided by ergmConstraint
s and, for valued ERGMs, by ergmReference
s.
The reference measure \((Y,h(y))\) is specified on the right-hand side of a one-sided formula passed
typically as the reference
argument.
ergm:::.formatIndexHtml(ergm:::.buildTermsDataframe("ergmReference"))
ergm:::.formatMatrixHtml(ergm:::.termMatrix("ergmReference"))
ergm:::.formatTocHtml(ergm:::.termToc("ergmReference"))
Hunter DR, Handcock MS, Butts CT, Goodreau SM, Morris M (2008b). ergm: A Package to Fit, Simulate and Diagnose Exponential-Family Models for Networks. Journal of Statistical Software, 24(3). tools:::Rd_expr_doi("10.18637/jss.v024.i03")
Krivitsky PN (2012). Exponential-Family Random Graph Models for Valued Networks. Electronic Journal of Statistics, 2012, 6, 1100-1128. tools:::Rd_expr_doi("10.1214/12-EJS696")
ergm
, network
, sna, summary.ergm
, print.ergm
, \%v\%
, \%n\%