Using as basis the common structure of this total sample, a set of JRR replications is defined. Each replication is formed such that when a unit is to be excluded in its construction, it is excluded simultaneously from every wave where the unit appears. For each replication, the required measure is constructed for each of the cross-sectional samples involved, and these measures are used to obtain the required averaged measure for the replication, from which variance is then estimated in the usual way.