Network collection
A network collection is a collection or sequence of several networks that belong together, e.g., by building a longitudinal network. You can define a network collection by pressing the collection manager button in visone's toolbar. There must be one node attribute that is specified for all included networks so that each attribute value is distinct in each individual network but occurs in all networks of the collection. Such an attribute is called \emph{identifying} attribute, since it is necessary to identify nodes that represent same actors in each observation. If no identifying attribute exists, a network collection cannot be defined. Usually, the node attribute \texttt{id} can serve as identifying attribute, but it is also possible to define another. A network collection is marked as being siena compatible if all included networks contain the same number of nodes. Only network collections that are siena compatible in this sense can be analysed. All operations are performed on the \emph{active} network collection that can be set in the network collection diaglogue.