Examining time-invariance in reliability in multi-wave, multi-indicator models: a covariance structure analysis approach accounting for indicator specificity.

A covariance structure analysis method for testing time-invariance in reliability in multiwave, multiple-indicator models in outlined. The approach accounts for observed variable specificity and permits, in addition, estimation of reliability in terms of 'pure' measurement error variance. The proposed procedure is developed within a confirmatory factor analysis framework and illustrated with data from a cognitive intervention study.