# nodecovar-ergmTerm: Covariance of undirected dyad values incident on each actor In ergm: Fit, Simulate and Diagnose Exponential-Family Models for Networks

 nodecovar-ergmTerm R Documentation

## Covariance of undirected dyad values incident on each actor

### Description

This term adds one statistic equal to ∑_{i,j<k} y_{i,j}y_{i,k}/(n-2) . This can be viewed as a valued analog of the star(2) statistic.

### Usage

# valued: nodecovar(center, transform)

### Arguments

 center If center=TRUE , the y_{\cdot,\cdot} s are centered by their mean over the whole network before the calculation. Note that this makes the model non-local, but it may alleviate multimodailty. transform If transform="sqrt" , y_{\cdot,\cdot} s are repaced by their square roots before the calculation. This makes sense for counts in particular. If center=TRUE as well, they are centered by the mean of the square roots.

### Note

Note that this term replaces nodesqrtcovar , which has been deprecated in favor of nodecovar(transform="sqrt") .