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Using Multigroup-Multiphase Latent State-Trait Models To Study Treatment-Induced Changes In Intra-Individual State Variability: An Application To Smokers' Affect, Christian Geiser, Daniel Griffin, Saul Shiffman

Psychology Faculty Publications

Sometimes, researchers are interested in whether an intervention, experimental manipulation, or other treatment causes changes in intra-individual state variability. The authors show how multigroup-multiphase latent state-trait (MG-MP-LST) models can be used to examine treatment effects with regard to both mean differences and differences in state variability. The approach is illustrated based on a randomized controlled trial in which N = 338 smokers were randomly assigned to nicotine replacement therapy (NRT) vs. placebo prior to quitting smoking. We found that post quitting, smokers in both the NRT and placebo group had significantly reduced intra-individual affect state variability with respect to the …