Methods Subjects The data for this paper selleck kinase inhibitor come from a longitudinal study of the natural history of smoking among adolescents. The study uses a multimethod approach to assess adolescents at multiple time points (baseline, 6, 15, and 24 months). The data collection modalities include paper-and-pencil questionnaires, in-person interviews, and for subsets of participants, more intensive measurement modalities including family observations, psychophysiological assessments, and week-long time/event ecological momentary assessment sampling via hand-held palmtop computers (referred to as ��Electronic Diary��). The NDSS instrument examined in this study was collected from questionnaires.

Out of the 1,263 baseline adolescents who had smoked and were eligible to respond to the NDSS items, 1,034 responded to at least 1 out of the 10 NDSS items and are included in the baseline analysis (Model I in the analysis and result sections). An averaged NDSS score was created for subjects who responded to at least five NDSS items at a given wave of data collection, resulting in a sample of 1,032 adolescents for the longitudinal NDSS score analysis (Model II). Those subjects who responded to at least one NDSS item at one or more time points are included in the longitudinal analysis of item responses (Model III), resulting in the largest sample size among the three sets of analyses, N = 1,097. Of the 1,097, the adolescents were either in Grade 9 (n = 545, 49.7%) or Grade 10 (n = 552, 50.3%), and 612 (55.8%) were female students. The ethnicity groups include Non-Hispanic White (618, 56.

3%), Non-Hispanic Black (172, 15.7%), Hispanic (204, 18.6%), Asian/Pacific Island (39, 3.6%), and other (64, 5.8%). Measures The 10 NDSS items were rated on a four-category ordinal scale (1 = not at all true; 2 = not very true; 3 = fairly true; 4 = very true). About one-fifth of the subjects missed information on at least one item at each wave. Brefeldin_A An average NDSS score was obtained for those individuals who responded to at least five items at a given time point. Descriptions and summary statistics for the items and the averaged score across waves are listed in Table 1. The subjects had a consistently high rating to Item 2, Since I started smoking, I have increased how much I smoke. Two other relatively highly rated items were: Item 1, Compared with when I first started smoking, I need to smoke a lot more now in order to be satisfied, and Item 3, After not smoking for awhile, I need to smoke to relieve feelings of restlessness and irritability.