Reliability in latent growth curve models

In this chapter I give an overview of reliability in the context of latent growth curve models. Although conceptually similar to latent factor models, reliability is more complex in a growth context. Two different conceptions of reliability were compared: growth curve reliability and growth rate reliability. The former evaluates the reliability of a measurement at a specific time point, the latter evaluates the reliability of the estimate of change over time. The differences, strengths, and limitations of these approaches are discussed, and demonstrated with an example on memory change in older adults. I show that using multiple measurements at each time point (with a second-order latent growth curve model) can improve growth curve reliability but will not necessarily improve growth rate reliability.