ergm.bounddeg: initializes the parameters to bound degree during sampling
Description
Not normally called directly by user, ergm.bounddeg initializes the list of parameters used to bound the degree during the Metropolis Hastings sampling process, and issues warnings if the original network doesn't meet the constraints specified by 'bounddeg'.Usage
ergm.bounddeg(bounddeg, nw)
Arguments
bounddeg
a list of parameters which may contain the following for a network of size n nodes:
- attribs: an nxp matrix, where entry ij is TRUE if node i has
attribute j, and FALSE otherwise; default=an nx1 matrix
of 1's
Value
- a list of parameters used to bound degree during sampling
- condAllDegExact: always FALSE
- attribs : as defined above
- maxout : as defined above
- maxin : as defined above
- minout : as defined above
- minin : as defined above
Details
In some modeling situations, the degree of certain nodes are constrained to
lie in a certain range (rather than their theoretically possible range
of 0 to n-1). Such sample space constraints may be incorporated into the
ergm modeling process, and if so then the MCMC routine is prevented from
visiting network states that violate any of these bounds.
In case there are categories of nodes and degree bounds for each set of
categories, such constraints may be incorporated as well. For instance,
if the nodes are girls and boys, and there is a maximum of 5 out-ties to boys and a maximum of 5 out-ties to girls for each node, we would define p to be 2, and the nxp matrix attribs would have TRUE in the first column (say) for exactly those nodes that are boys and TRUE in the second column for only the girls. The maxout matrix would consist of all 5s in this case, and the other arguments would be left as their default values.
Since the observed network is generally the beginning of the Markov chain, it must satisfy all of the degree constraints itself; thus, this function returns an error message if any bound is violated by the observed network.