ergm (version 3.0-3)

stergm: Separable Temporal Exponential Family Random Graph Models

Description

stergm is used for finding Separable Temporal ERGMs' (STERGMs) Conditional MLE (CMLE) (Krivitsky and Handcock, 2010) and Equilibrium Generalized Method of Moments Estimator (EGMME) (Krivitsky, 2009).

Usage

stergm (nw, 
          formation, 
          dissolution, 
          estimate, 
          times=NULL, 
          offset.coef.form=NULL, 
          offset.coef.diss=NULL,
          targets=NULL, 
          target.stats=NULL,
          eval.loglik=FALSE,
          control=control.stergm(),
          verbose=FALSE, 
          ...)

Arguments

nw

A network object (for EGMME); or networkDynamic object, a network.list

formation, dissolution

One-sided ergm-style formulas for the formation and dissolution models, respectively.

estimate

One of "EGMME" for Equilibrium Generalized Method of Moments Estimation, based on a single network with some temporal information and making an assumption that it is a product of a STERGM process running to its stationary (equilibrium) distrib

times

For CMLE and CMPLE estimation, times or indexes at which the networks whose transition is to be modeled are observed. Default to c(0,1) if nw is a networkDyna

offset.coef.form

Numeric vector to specify offset formation parameters.

offset.coef.diss

Numeric vector to specify offset dissolution parameters.

targets

One-sided ergm-style formula specifying statistics whose moments are used for the EGMME. Unused for CMLE and CMPLE.

target.stats

A vector specifying the values of the targets statistics that EGMME will try to match. Defaults to the statistics of nw. Unused for CMLE and CMPLE.

eval.loglik

Whether or not to calculate the log-likelihood of a CMLE STERGM fit. See ergm for details.

control

A list of control parameters for algorithm tuning. Constructed using control.stergm.

verbose

logical or integer; if TRUE or positive, the program will print out progress information. Higher values result in more output.

...

Additional arguments, to be passed to lower-level functions.

Value

• stergm returns an object of class stergm that is a list consisting of the following elements:
• formation, dissolution
  Formation and dissolution formulas, respectively.
• targets
  The targets formula.
• target.stats
  The target statistics.
• estimate
  The type of estimate.
• opt.history
  A matrix containing the full trace of the EGMME optimization process: coefficients tried and target statistics simulated.
• sample
  An mcmc object containing target statistics sampled at the estimate.
• covar
  The full estimated variance-covariance matrix of the parameter estimates for EGMME. (Note that although the CMLE formation parameter estimates are independent of the dissolution parameter estimates due to the separability assumption, this is not necessarily the case for EGMME.)
• formation.fit, dissolution.fit
  For CMLE and CMPLE, ergm objects from fitting formation and dissolution, respectively. For EGMME, stripped down ergm-like lists.
• network
  The original network.
• control
  The control parameters used to fit the model.
• See the method print.stergm for details on how an stergm object is printed. Note that the method summary.stergm returns a summary of the relevant parts of the stergm object in concise summary format.

Model Terms

See ergm and ergm-terms for details. At this time, only linear ERGM terms are allowed.

References

Krivitsky PN (2009). Statistical Models for Social Network Data and Processes. PhD Thesis. University of Washington.

Krivitsky PN, Handcock MS (2010). A Separable Model for Dynamic Networks. http://arxiv.org/abs/1011.1937

See Also

network, %v%, %n%, ergm-terms