Based on model fit statistics and parsimony, a five class trajectory model was chosen. Although the adjusted Lo-Mendell-Rubin test suggested retaining a six-class model, there was no improvement in the BIC for the six-class model, and the average posterior probabilities dropped below 0.70 for two of the classes, suggesting a loss in classification quality. While the BIC was slightly higher for the four-class model than for the five-class model, this difference was minimal and represented virtually no improvement in model fit. Additionally, the Lo-Mendell-Ruben test for the five-class model was significant at p<.05, providing additional evidence for retaining the five-class model. Finally, the five classes differed significantly in their smoking behavior, providing substantive evidence in support of a five-class solution.
