ergm (version 2.0-5)

summary.statistics: Calculation of network or graph statistics

Description

Used to calculate the specified statistics for an observed network if its argument is a formula for an ergm. See ergm-terms for more information on the statistics that may be specified.

Usage

## S3 method for class 'formula':
summary.statistics(object, \dots, drop=FALSE, basis=NULL)
## S3 method for class 'ergm':
summary.statistics(object, \dots, drop=FALSE, basis=NULL)

Arguments

object

an Robject. It is either an Rformula object (see above) or an ergm model object. In the latter case, summary.statistics is called fo

drop

logical: Should terms whose observed statistics are extreme among the set of all possible network statistics (which result in nonexistent MLEs) be dropped?

basis

An optional network object relative to which the global statistics should be calculated.

...

further arguments passed to or used by methods.

Value

• A vector of statistics measured on the network.

Details

If object is of class formula, then summary may be used in lieu of summary.statistics because summary.formula calls the summary.statistics function. The function actually cumulates the change statistics when removing edges from the observed network one by one until the empty network results. Since each model term has a prespecified value (zero by default) for the corresponding statistic(s) on an empty network, these change statistics give the absolute statistics on the original network.

See Also

ergm, network, ergm-terms

Examples

#
# Lets look at the Florentine marriage data
#
data(florentine)
#
# test the summary.statistics function
#
summary(flomarriage ~ edges + kstar(2))
m <- as.matrix(flomarriage)
summary(m ~ edges)  # twice as large as it should be
summary(m ~ edges, directed=FALSE) # Now it's correct