A well documented data set was available to test these hypotheses. LRI were documented during the first three years of life, atopy was evaluated, symptom status tracked, and lung function periodically measured. Infant lung function was assessed for a sample of the children and methacholine challenge was performed at age 11. In the evaluation at age 16 years, symptoms, lung function, including methacholine responsiveness, and atopy and lymphocyte phenotype were assessed. Various methods for longitudinal data analysis were used.