B-ergmTerm {ergm}

Wrap binary terms for use in valued models

Description

Wraps binary ergm terms for use in valued models, with formula specifying which terms are to be wrapped and form specifying how they are to be used and how the binary network they are evaluated on is to be constructed.

Usage

# valued: B(formula, form)

Arguments

formula

a one-sided ergm()-style formula whose RHS contains the binary ergm terms to be evaluated. Which terms may be used depends on the argument form

form

One of three values:

• "sum": see section "Generalizations of binary terms" in ergmTerm help; all terms in formula must be dyad-independent.

• "nonzero": section "Generalizations of binary terms" in ergmTerm help; any binary ergm terms may be used in formula .

• a one-sided formula value-dependent network. form must contain one "valued" ergm term, with the following properties:

  • dyadic independence;

  • dyadwise contribution of either 0 or 1; and

  • dyadwise contribution of 0 for a 0-valued dyad.

  Formally, this means that it is expressable as

  g(y) = \sum_{i,j} f_{i,j}(y_{i,j}),

  where for all i, j, and y, f_{i,j}(y_{i,j}) is either 0 or 1 and, in particular, f_{i,j}(0)=0.

  Examples of such terms include nonzero , ininterval() , atleast() , atmost() , greaterthan() , lessthen() , and equalto() .

  Then, the value of the statistic will be the value of the statistics in formula evaluated on a binary network that is defined to have an edge if and only if the corresponding dyad of the valued network adds 1 to the valued term in form .

Details

For example, B(~nodecov("a"), form="sum") is equivalent to nodecov("a", form="sum") and similarly with form="nonzero" .

When a valued implementation is available, it should be preferred, as it is likely to be faster.

See Also

ergmTerm for index of model terms currently visible to the package.

Keywords

operator, valued