The gears in network dynamics: The alter-trajectory approach.

Egocentric networks are dynamic. Prior research has typically measured change in broad network characteristics or simply in membership turnover but given relatively little attention to the history of alter-ego relationships. Using rich information about alters over three waves in the UCNets study, we develop a novel approach that delineates a "trajectory" over time for each of the alters in the network and then uses all these observed trajectories to identify types of ego networks. Results from Multilevel Latent Growth Models reveal six distinct trajectories for alters: continuously active, awakened, dormant, dropped, transitory, and new. The distribution of those six trajectories coalesces at the ego-level into three network types - anchored, shifting, and regenerative - each with unique dynamics and compositional features. To illustrate the contribution of this approach, we examine the associations between life events and the three types of network dynamics among UCNets' young adults. Findings reveal subtle patterns of change: some events shape networks by reinforcing their cores, while others expand or reconfigure networks' near and distant peripheries.