Using latent class and latent transition analysis to examine the transtheoretical model staging algorithm and sequential stage transition in adolescent smoking.

Data on stage of change was collected between 1997-1999 on 4125 adolescent nonsmokers and smokers from central England who completed two versions of the stage of change algorithm for smoking acquisition and cessation. The fit of the latent variable defined by the spiral of change to adolescents' responses to the staging questions was examined using latent class analysis. Whether a model of sequential transition across stages fitted the observed transitions was tested with latent transition analysis (LTA). There was reasonable support for the staging algorithm but no evidence of sequential stage transition. The research was funded by Cancer Research UK.